Charles University LF2 Entrance Exam Sample Test with Answers

Section	Questions	Time	Marks (Medicine Entrance Examination)
Medicine Entrance Examination	75	90 min	+3 correct, 0 wrong, 0 blank

Question 1

Biology · Introduction to Biology · Foundation

Which of the following statements about the scientific (binomial) names of species are correct? Select all correct answers.

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Answer: A

A is true: in Homo sapiens, Homo is the genus. B is false: the genus name always starts with a capital letter, while the specific epithet is written in lower case. C is false: two species of one genus must differ in their epithet, otherwise they would have the same name. D is false: scientific names are written in Latin or latinised form, whatever the country. So only A is correct.

Question 2

Biology · Cell Biology · Standard

Which of the following statements about mitochondria are correct? Select all correct answers.

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Answer: A, B, C, D

A is true: mitochondria carry a small circular DNA molecule, inherited through the mother. B is true: they have an outer membrane and a folded inner membrane forming the cristae. C is true: the electron transport chain and ATP synthase sit in the inner membrane, where oxidative phosphorylation takes place. D is true: mitochondria have their own ribosomes and make some of their own proteins. So all four are correct.

Question 3

Biology · Cell Biology · Standard

Which of the following statements about transport across the plasma membrane are correct? Select all correct answers.

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Answer: B

A is false: simple diffusion is passive and runs down a concentration gradient without ATP. B is true: the Na⁺/K⁺-ATPase exchanges 3 Na⁺ out for 2 K⁺ in per ATP, which is active transport. C is false: water moves towards the solution with the higher solute concentration (lower water potential). D is false: facilitated diffusion uses carrier or channel proteins but is still passive, so it only runs down the gradient. So only B is correct.

Question 4

Biology · Molecular Biology · Foundation

Which of the following nitrogenous bases are found in RNA but not in DNA? Select all correct answers.

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Answer: D

A is false: adenine occurs in both DNA and RNA. B is false: guanine also occurs in both. C is false: thymine is found in DNA, where RNA has uracil instead. D is true: uracil is the RNA base that pairs with adenine and is not a normal component of DNA. So only D is correct.

Question 5

Biology · Molecular Biology · Challenging

Which of the following statements about DNA replication are correct? Select all correct answers.

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Answer: A, B, D

A is true: this is what the Meselson and Stahl experiment showed. B is true: DNA polymerase adds nucleotides only to the 3′ end of a growing strand. C is false: Okazaki fragments are made on the lagging strand, which is synthesised discontinuously; the leading strand is made continuously. D is true: the S (synthesis) phase of interphase is when DNA is copied. So A, B and D are correct.

Question 6

Biology · Molecular Biology · Challenging

The coding region of an mRNA, from the first nucleotide of the start codon to the last nucleotide of the stop codon, is 300 nucleotides long. How many amino acids does the polypeptide translated from it contain, before any processing? Select all correct answers.

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Answer: C

A is false: each amino acid is coded by three nucleotides, not one. B is false: 300 ÷ 3 gives 100 codons, but the last of them is the stop codon, which codes for no amino acid. C is true: 100 codons minus the stop codon leaves 99 codons, so 99 amino acids, the first of them methionine from the start codon. D is false: 150 would assume two nucleotides per codon. So only C is correct.

Question 7

Biology · Molecular Biology · Challenging

Which of the following statements about gene expression are correct? Select all correct answers.

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Answer: A, C

A is true: splicing of pre-mRNA takes place in the nucleus before the mature mRNA is exported. B is false: ribosomes read mRNA from its 5′ end towards its 3′ end. C is true: bacteria have no nuclear envelope, so ribosomes can attach to an mRNA that is still being transcribed. D is false: RNA polymerase starts a new chain on its own at a promoter; it is DNA polymerase that needs a primer. So A and C are correct.

Question 8

Biology · Genetics · Foundation

Two parents are both heterozygous (Aa) for a gene with a completely dominant allele A. Which of the following statements about their offspring are correct? Select all correct answers.

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Answer: A, B, C

A is true: AA and Aa both show the dominant trait, giving 3 : 1. B is true: the Punnett square gives AA, Aa, aA and aa, that is 1 : 2 : 1. C is true: one square in four is aa, so 25%. D is false: one in three of the dominant offspring is AA, homozygous, so not all of them are heterozygous. So A, B and C are correct.

Question 9

Biology · Genetics · Standard

Haemophilia A is inherited as an X-linked recessive trait. A woman who is a carrier has a child with a man who does not have haemophilia. Assuming no new mutation, what is the probability that the child will be a boy with haemophilia? Select all correct answers.

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Answer: B

The chance that the child is a boy is 1/2, and a boy receives his only X chromosome from his mother, who passes on the affected X with a chance of 1/2. Multiplying gives 1/2 × 1/2 = 1/4. A is false: 1/2 is the chance that a son is affected, not that a child is an affected son. C is false: 1/8 multiplies by a factor that does not apply. D is false: the father's X is normal, but sons do not receive it, so affected sons are possible. So only B is correct.

Question 10

Biology · Genetics · Challenging

A man with blood group A, whose mother had blood group O, has a child with a woman with blood group AB. Which blood groups (ABO system) could the child have? Select all correct answers.

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Answer: A, B, C

The man received an i allele from his group O mother, so he is Iᴬi; the woman is IᴬIᴮ. A is true: Iᴬ from either parent with Iᴬ or i gives group A. B is true: the father's i with the mother's Iᴮ gives Iᴮi, group B. C is true: the father's Iᴬ with the mother's Iᴮ gives group AB. D is false: group O needs ii, and the mother has no i allele to pass on. So A, B and C are correct.

Question 11

Biology · Biology of Bacteria and Viruses · Standard

Which of the following statements about bacteria and viruses are correct? Select all correct answers.

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Answer: A, B

A is true: bacteria make their own proteins on their own (70S) ribosomes. B is true: peptidoglycan is the characteristic component of the bacterial cell wall, and it is the target of penicillin. C is false: viruses have no metabolism of their own and multiply only inside living host cells. D is false: influenza is caused by a virus, and antibiotics such as penicillin act on bacterial structures that viruses do not have. So A and B are correct.

Question 12

Biology · Biology of Plants and Fungi · Standard

Which of the following polysaccharides do fungi use as their main energy store? Select all correct answers.

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Answer: C

A is false: starch is the storage polysaccharide of plants. B is false: chitin is a structural polysaccharide that builds the fungal cell wall, not an energy store. C is true: fungi, like animals, store glucose as glycogen. D is false: cellulose is the structural polysaccharide of plant cell walls. So only C is correct.

Question 13

Biology · Biology of Animals and Protists · Standard

Which of the following organisms are protists? Select all correct answers.

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Answer: B

A is false: Candida albicans is a yeast, so a fungus. B is true: Plasmodium falciparum, the cause of the most dangerous form of malaria, is a unicellular eukaryote classed among the protists (apicomplexans). C is false: Escherichia coli is a bacterium, a prokaryote. D is false: Taenia solium, the pork tapeworm, is a multicellular animal (a flatworm). So only B is correct.

Question 14

Biology · Human Biology · Foundation

Which of the following blood vessels carry oxygenated blood from the lungs to the heart? Select all correct answers.

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Answer: C

A is false: the aorta carries oxygenated blood away from the heart to the body. B is false: the pulmonary artery carries deoxygenated blood from the right ventricle to the lungs. C is true: the pulmonary veins return oxygenated blood from the lungs to the left atrium. D is false: the superior vena cava returns deoxygenated blood from the upper body to the right atrium. So only C is correct.

Question 15

Biology · Human Biology · Standard

Which of the following hormones are produced by the adrenal glands? Select all correct answers.

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Answer: B, C, D

A is false: insulin is made by the beta cells of the islets of Langerhans in the pancreas. B is true: adrenaline is released by the adrenal medulla. C is true: cortisol is a glucocorticoid made by the adrenal cortex. D is true: aldosterone is a mineralocorticoid made by the adrenal cortex. So B, C and D are correct.

Question 16

Biology · Human Biology · Standard

In a healthy person, in which part of the nephron is almost all of the filtered glucose reabsorbed? Select all correct answers.

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Answer: B

A is false: the glomerulus is where blood plasma is filtered into the capsule, not where substances are reabsorbed. B is true: glucose is reabsorbed by carrier proteins in the proximal convoluted tubule, so normally none reaches the urine. C is false: the loop of Henle mainly concentrates the medulla through water and salt movements. D is false: the collecting duct adjusts water reabsorption under the control of ADH. So only B is correct.

Question 17

Biology · Human Biology · Challenging

Which of the following statements about human digestion are correct? Select all correct answers.

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Answer: A, C

A is true: pepsin acts in the stomach, where hydrochloric acid keeps the pH low. B is false: bile contains no digestive enzymes; its bile salts emulsify fats, and the fats are hydrolysed by pancreatic lipase. C is true: trypsin is secreted as inactive trypsinogen, which is activated in the small intestine, so the pancreas does not digest itself. D is false: salivary amylase hydrolyses starch, not proteins. So A and C are correct.

Question 18

Biology · Evolutionary Biology · Standard

Which of the following pairs are homologous structures? Select all correct answers.

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Answer: D

Homologous structures share an evolutionary origin even if their function differs. A is false: insect and bird wings evolved independently, so they are analogous. B is false: cactus spines are modified leaves and hedgehog spines are modified hairs, so they are analogous. C is false: the similar shape of a fish and a mammal is the result of convergent evolution. D is true: both are the forelimb of a mammal, built on the same pattern of bones. So only D is correct.

Question 19

Biology · Ecology and Environment Protection · Foundation

In the food chain grass → grasshopper → frog → snake, which of the organisms are secondary consumers? Select all correct answers.

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Answer: C

A is false: grass is the producer. B is false: the grasshopper eats the producer, so it is the primary consumer. C is true: the frog eats the primary consumer, so it is the secondary consumer. D is false: the snake eats the secondary consumer, so it is the tertiary consumer. So only C is correct.

Question 20

Biology · History of Biology · Standard

Which of the following statements about the history of biology are correct? Select all correct answers.

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Answer: A, C, D

A is true: Mendel presented his pea experiments in 1865 and published them in 1866. B is false: the theory of evolution by natural selection was put forward by Charles Darwin and Alfred Russel Wallace; Pasteur is known for disproving spontaneous generation and for vaccines. C is true: Watson and Crick published the double-helix model in 1953. D is true: Fleming discovered penicillin in 1928. So A, C and D are correct.

Question 21

Physics and Biophysics · Basic Terms · Foundation

Which of the following are base units of the International System of Units (SI)? Select all correct answers.

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Answer: A, C

A: true, the kilogram is the SI base unit of mass. B: false, the newton is a derived unit, 1 N = 1 kg m s⁻². C: true, the ampere is the SI base unit of electric current. D: false, the joule is a derived unit, 1 J = 1 kg m² s⁻². So A and C are correct.

Question 22

Physics and Biophysics · Mechanics · Foundation

A car starts from rest and accelerates uniformly at 2 m/s² for 5 s. Which of the following statements are true? Select all correct answers.

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Answer: C

The final speed is v = at = 2 × 5 = 10 m/s, and the distance is s = ½at² = ½ × 2 × 25 = 25 m. A: false, it travels 25 m, not 50 m. B: false, the average speed is 25 m ÷ 5 s = 5 m/s (half the final speed, since it started from rest). C: true. D: false, 20 m/s would need 4 m/s². So only C is correct.

Question 23

Physics and Biophysics · Mechanics · Standard

A ball of mass 1 kg is thrown vertically upwards at 20 m/s. Take g = 10 m/s² and neglect air resistance. Which of the following statements are true? Select all correct answers.

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Answer: B, C, D

A: false, at the top the velocity is momentarily zero but gravity still acts, so the acceleration is 10 m/s² downwards throughout. B: true, h = v²/(2g) = 400/20 = 20 m. C: true, t = v/g = 20/10 = 2 s. D: true, Ek = ½mv² = ½ × 1 × 400 = 200 J. So B, C and D are correct.

Question 24

Physics and Biophysics · Mechanics · Challenging

A trolley of mass 2 kg moving at 3 m/s collides with a stationary trolley of mass 1 kg on a frictionless track. The two trolleys stick together. Which of the following statements are true? Select all correct answers.

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Answer: C

Momentum is conserved: 2 × 3 = 6 kg m/s before and after, so the common speed is 6 ÷ 3 = 2 m/s. Kinetic energy before is ½ × 2 × 9 = 9 J, after is ½ × 3 × 4 = 6 J. A: false, the momentum is still 6 kg m/s. B: false, a collision in which the bodies stick together is inelastic. C: true. D: false, 9 − 6 = 3 J is converted, not 2 J. So only C is correct.

Question 25

Physics and Biophysics · Vibration, Waves and Acoustics · Standard

A sound wave of frequency 680 Hz travels through air at 340 m/s. Which of the following statements are true? Select all correct answers.

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Answer: B

λ = v/f = 340/680 = 0.5 m. A: false, 2 m comes from dividing frequency by speed, the wrong way round. B: true. C: false, sound in air is a longitudinal wave of compressions and rarefactions. D: false, the speed of sound depends on the medium (and its temperature), not on the frequency; doubling the frequency halves the wavelength. So only B is correct.

Question 26

Physics and Biophysics · Vibration, Waves and Acoustics · Challenging

A body on an ideal spring oscillates horizontally without friction (simple harmonic motion). Which of the following statements are true? Select all correct answers.

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Answer: A, C, D

For a mass on a spring T = 2π√(m/k). A: true, √4 = 2, so the period doubles. B: false, the restoring force and so the acceleration (a = −ω²x) are greatest at maximum displacement; it is the velocity that is zero there. C: true, the formula contains no amplitude. D: true, at equilibrium all the energy is kinetic. So A, C and D are correct.

Question 27

Physics and Biophysics · Thermodynamics · Standard

How much heat is needed to warm 2 kg of water from 20 °C to 70 °C? Take the specific heat capacity of water as 4200 J/(kg K) and ignore heat losses. Select all correct answers.

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Answer: B

Q = mcΔT = 2 × 4200 × 50 = 420 000 J = 420 kJ. A: false, a factor of ten too small. B: true. C: false, this is the heat for 1 kg. D: false, this would warm 2 kg by 100 K. So only B is correct.

Question 28

Physics and Biophysics · Thermodynamics · Challenging

Which of the following statements about a fixed amount of an ideal gas are true? Select all correct answers.

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Answer: A, B, C, D

A: true, at constant volume p/T is constant. B: true, the internal energy of an ideal gas depends only on its temperature, which an isothermal process keeps fixed. C: true, in an adiabatic compression no heat leaves, so the work done on the gas raises its internal energy and temperature. D: true, at constant pressure V/T is constant and 600 K is twice 300 K. So A, B, C and D are all correct.

Question 29

Physics and Biophysics · Molecular Physics · Foundation

Which of the following statements about the particles of matter are true? Select all correct answers.

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Answer: A

A: true, the grains jitter because they are struck unevenly by moving water molecules. B: false, particles in a solid vibrate about fixed positions. C: false, the mean kinetic energy of gas molecules is proportional to the absolute temperature. D: false, molecules are far closer together in the liquid than in the vapour. So only A is correct.

Question 30

Physics and Biophysics · Molecular Physics · Standard

Which of the following statements about surface tension and capillarity are true? Select all correct answers.

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Answer: A, B, D

A: true, water wets glass and is drawn up. B: true, mercury does not wet glass, so it is depressed (capillary depression). C: false, the capillary rise is inversely proportional to the radius, so a narrower tube gives a higher rise. D: true, detergents are surfactants and reduce surface tension. So A, B and D are correct.

Question 31

Physics and Biophysics · Electricity and Magnetism · Foundation

A 6 Ω resistor is connected across a 12 V supply. Which of the following statements are true? Select all correct answers.

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Answer: D

I = U/R = 12/6 = 2 A and P = UI = 12 × 2 = 24 W. A: false, 0.5 A is R/U. B: false, the power is 24 W. C: false, the resistance of an ohmic resistor does not depend on the voltage; doubling the voltage doubles the current. D: true. So only D is correct.

Question 32

Physics and Biophysics · Electricity and Magnetism · Standard

A 4 Ω resistor and a 12 Ω resistor are connected in parallel across a 6 V supply of negligible internal resistance. Which of the following statements are true? Select all correct answers.

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Answer: B, D

A: false, in parallel each resistor has the full 6 V across it. B: true, R = (4 × 12)/(4 + 12) = 48/16 = 3 Ω. C: false, the 4 Ω resistor carries 6/4 = 1.5 A; 0.5 A is the current through the 12 Ω resistor. D: true, 6/3 = 2 A, which equals 1.5 + 0.5 A. So B and D are correct.

Question 33

Physics and Biophysics · Electricity and Magnetism · Challenging

A 2 μF capacitor and a 3 μF capacitor are connected in series to a 10 V supply and fully charged. Which of the following statements are true? Select all correct answers.

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Answer: B

In series 1/C = 1/2 + 1/3 = 5/6, so C = 1.2 μF. A: false, 5 μF is the parallel value. B: true, both carry the same charge Q = CU = 1.2 μF × 10 V = 12 μC. C: false, the 2 μF capacitor has 12/2 = 6 V across it (and the 3 μF one 4 V). D: false, W = ½CU² = ½ × 1.2 μF × 100 V² = 60 μJ. So only B is correct.

Question 34

Physics and Biophysics · Electricity and Magnetism · Standard

A proton moves through a uniform magnetic field with its velocity perpendicular to the field lines. Neglect gravity and any electric field. Which of the following statements are true? Select all correct answers.

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Answer: C

The magnetic (Lorentz) force F = qvB acts perpendicular to the velocity. A: false, a force perpendicular to the motion changes only the direction, not the speed. B: false, the proton moves in a circle. C: true, a force always perpendicular to the displacement does no work. D: false, it is perpendicular, not parallel. So only C is correct.

Question 35

Physics and Biophysics · Electromagnetic Radiation · Foundation

Which of the following statements about electromagnetic waves are true? Select all correct answers.

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Answer: D

A: false, X-rays have a much shorter wavelength than visible light. B: false, infrared has a lower frequency than ultraviolet, so its photons carry less energy (E = hf). C: false, all electromagnetic waves, radio included, travel through a vacuum. D: true, all travel at c ≈ 3.0 × 10⁸ m/s in a vacuum. So only D is correct.

Question 36

Physics and Biophysics · Electromagnetic Radiation · Standard

Which of the following statements about photons and the photoelectric effect are true? Select all correct answers.

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Answer: A, C

A: true, E = hf. B: false, below the threshold frequency no single photon has enough energy to free an electron, however many photons arrive. C: true, E = hc/λ, so doubling the wavelength halves the energy. D: false, greater intensity means more photons and so more photoelectrons, but each photon has the same energy, so the maximum kinetic energy (hf − W) is unchanged. So A and C are correct.

Question 37

Physics and Biophysics · Optics · Standard

An object is placed 30 cm in front of a thin converging lens of focal length 10 cm. Which of the following statements are true? Select all correct answers.

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Answer: D

From 1/f = 1/a + 1/a′: 1/a′ = 1/10 − 1/30 = 2/30, so a′ = 15 cm, positive, so the image is real and on the far side. The magnification is 15/30 = 0.5, so the image is inverted and half the size. A: false, it is real. B: false, it is diminished. C: false, the power is 1/0.10 m = +10 D. D: true. So only D is correct.

Question 38

Physics and Biophysics · Optics · Challenging

Light travels between air (refractive index 1.0) and a glass of refractive index 1.5. Take the speed of light in a vacuum as 3.0 × 10⁸ m/s. Which of the following statements are true? Select all correct answers.

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Answer: A

A: true, v = c/n = 3.0 × 10⁸ / 1.5 = 2.0 × 10⁸ m/s. B: false, entering an optically denser medium the ray bends towards the normal. C: false, total internal reflection needs light travelling from the denser into the less dense medium. D: false, sin C = 1/1.5 ≈ 0.67, so C ≈ 42°; a critical angle of 30° (sin 30° = 0.5) would need n = 2. So only A is correct.

Question 39

Physics and Biophysics · Atomic and Nuclear Physics · Standard

A sample contains 80 g of a radioactive isotope whose half-life is 5 days. Which of the following statements about the mass of the isotope left after 15 days are true? Select all correct answers.

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Answer: C

15 days is three half-lives: 80 → 40 → 20 → 10 g. A: false, 20 g remains after two half-lives (10 days). B: false, 80/3 ≈ 26.7 g comes from dividing by the number of half-lives, but each half-life halves what is left. C: true. D: false, 5 g remains after four half-lives (20 days). So only C is correct.

Question 40

Physics and Biophysics · Atomic and Nuclear Physics · Standard

Uranium-238 has proton number 92. Which of the following statements are true? Select all correct answers.

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Answer: B

A: false, it has 238 − 92 = 146 neutrons. B: true, an alpha particle carries away 2 protons and 2 neutrons, so Z = 92 − 2 = 90 and A = 238 − 4 = 234 (thorium-234). C: false, in beta-minus decay a neutron becomes a proton, so the proton number rises by 1. D: false, a gamma photon carries energy only, so neither the proton number nor the nucleon number changes. So only B is correct.

Question 41

Chemistry · General Chemistry · Foundation

Sodium has atomic number 11. Which of the following statements about an atom of the nuclide ²³Na are correct? Select all correct answers.

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Answer: A, B, C

A is true: the atomic number is the number of protons, 11. B is true: neutrons = mass number − atomic number = 23 − 11 = 12. C is true: Na⁺ has lost one of the atom's 11 electrons, leaving 10. D is false: the mass number is 23; 11 is the atomic number. So A, B and C are correct.

Question 42

Chemistry · General Chemistry · Standard

Which of the following molecules contain a triple bond? Select all correct answers.

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Answer: C

A is false: the two oxygen atoms in O₂ share a double bond. B is false: carbon dioxide has two C=O double bonds. C is true: nitrogen atoms share three electron pairs, N≡N. D is false: ethene has one C=C double bond. So only C is correct.

Question 43

Chemistry · General Chemistry · Standard

For the exothermic equilibrium N₂(g) + 3 H₂(g) ⇌ 2 NH₃(g), which of the following changes shift the equilibrium towards ammonia? Select all correct answers.

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Answer: B

A is false: for an exothermic forward reaction, heating favours the reverse, endothermic direction. B is true: four moles of gas give two, so higher pressure favours the side with fewer gas molecules, ammonia. C is false: a catalyst speeds up both directions equally and does not move the equilibrium. D is false: removing a reactant shifts the equilibrium back towards the reactants. So only B is correct.

Question 44

Chemistry · General Chemistry · Challenging

Which of the following statements about the reaction Zn + Cu²⁺ → Zn²⁺ + Cu are correct? Select all correct answers.

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Answer: A, C, D

A is true: zinc loses electrons and its oxidation number rises from 0 to +2. B is false: Cu²⁺ accepts electrons, so it is the oxidising agent; zinc is the reducing agent. C is true: each Zn atom gives up two electrons, which one Cu²⁺ ion takes up. D is true: Cu²⁺ is reduced to copper metal, from +2 to 0. So A, C and D are correct.

Question 45

Chemistry · Inorganic Chemistry · Foundation

Which of the following statements about the halogens (group 17) are correct? Select all correct answers.

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Answer: A, B, C, D

A is true: the halogens have the valence configuration ns² np⁵, seven electrons. B is true: chlorine is a yellow-green gas under normal conditions. C is true: gaining one electron completes the octet, giving halide ions such as Cl⁻ in NaCl. D is true: fluorine has the highest electronegativity on the Pauling scale, about 4.0. So all four are correct.

Question 46

Chemistry · Inorganic Chemistry · Standard

Which of the following oxides react with water to form an acid? Select all correct answers.

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Answer: C

A is false: sodium oxide reacts with water to give sodium hydroxide, a base. B is false: calcium oxide gives calcium hydroxide, a base. C is true: sulfur trioxide, a non-metal oxide, reacts with water to give sulfuric acid, H₂SO₄. D is false: potassium oxide gives potassium hydroxide, a base. So only C is correct.

Question 47

Chemistry · Inorganic Chemistry · Standard

What is the oxidation number of manganese in potassium permanganate, KMnO₄? Select all correct answers.

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Answer: D

The oxidation numbers in a neutral compound add up to zero. Potassium is +1 and each of the four oxygens is −2, giving −8, so manganese must be +7: (+1) + (+7) + (−8) = 0. A, B and C are false: +2, +4 and +6 are manganese's states in Mn²⁺ salts, MnO₂ and the manganate ion MnO₄²⁻ respectively. D is true. So only D is correct.

Question 48

Chemistry · Inorganic Chemistry · Standard

Which of the following metals react with dilute hydrochloric acid to release hydrogen? Select all correct answers.

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Answer: C

Only a metal that stands before hydrogen in the reactivity (electrochemical) series can displace it from a non-oxidising acid. A is false: copper is less reactive than hydrogen. B is false: silver is less reactive than hydrogen. C is true: zinc reacts, Zn + 2 HCl → ZnCl₂ + H₂. D is false: gold is a noble metal and does not react. So only C is correct.

Question 49

Chemistry · Chemical Calculations · Foundation

How many moles of sodium hydroxide are there in 4 g of NaOH? (M(NaOH) = 40 g/mol) Select all correct answers.

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Answer: B

The amount of substance is mass divided by molar mass: n = 4 g ÷ 40 g/mol = 0.1 mol. A is false: 1 mol would be 40 g. B is true. C is false: 0.4 mol of NaOH would weigh 16 g. D is false: 10 comes from dividing the molar mass by the mass, the wrong way round. So only B is correct.

Question 50

Chemistry · Chemical Calculations · Standard

What is the pH of a hydrochloric acid solution with a concentration of 0.01 mol/L, assuming the acid is fully dissociated? Select all correct answers.

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Answer: D

HCl is a strong acid, so [H₃O⁺] = 0.01 mol/L = 10⁻² mol/L, and pH = −log[H₃O⁺] = 2. A is false: pH 1 would need 0.1 mol/L. B is false: pH 12 is the value for 0.01 mol/L of a strong base such as NaOH. C is false: 0.01 is the concentration, not the pH. D is true. So only D is correct.

Question 51

Chemistry · Chemical Calculations · Standard

50 mL of a 2 mol/L sodium chloride solution is diluted with water to a final volume of 200 mL. What is the concentration of the diluted solution? Select all correct answers.

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Answer: C

Dilution keeps the amount of solute constant: c₁V₁ = c₂V₂, so c₂ = 2 × 50 ÷ 200 = 0.5 mol/L. A is false: 8 mol/L multiplies instead of dividing by the dilution factor of 4. B is false: 1 mol/L would be a dilution only to 100 mL. C is true. D is false: 0.25 mol/L would need a final volume of 400 mL. So only C is correct.

Question 52

Chemistry · Chemical Calculations · Challenging

What mass of water is formed when 4 g of hydrogen burns completely in excess oxygen? (Ar(H) = 1, Ar(O) = 16) Select all correct answers.

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Answer: B

The equation is 2 H₂ + O₂ → 2 H₂O, so one mole of H₂ gives one mole of H₂O. 4 g of H₂ (M = 2 g/mol) is 2 mol, which gives 2 mol of water, 2 × 18 g = 36 g. A is false: 18 g is one mole of water. B is true. C is false: 32 g is the mass of oxygen that reacts (1 mol of O₂), not of water formed. D is false: 72 g would treat 4 g of hydrogen as 4 mol. So only B is correct.

Question 53

Chemistry · Organic Chemistry · Foundation

Which of the following functional groups are characteristic of carboxylic acids? Select all correct answers.

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Answer: D

A is false: −OH alone is the hydroxyl group of alcohols. B is false: −CHO is the aldehyde group. C is false: −NH₂ is the amino group of amines. D is true: the carboxyl group −COOH defines a carboxylic acid, as in acetic acid, CH₃COOH. So only D is correct.

Question 54

Chemistry · Organic Chemistry · Challenging

Which of the following compounds are isomers of butan-1-ol, CH₃CH₂CH₂CH₂OH? Select all correct answers.

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Answer: A, B, C

Isomers have the same molecular formula, here C₄H₁₀O, but a different structure. A is true: butan-2-ol, CH₃CH(OH)CH₂CH₃, is C₄H₁₀O. B is true: diethyl ether, CH₃CH₂OCH₂CH₃, is also C₄H₁₀O, a functional-group isomer. C is true: 2-methylpropan-2-ol, (CH₃)₃COH, is C₄H₁₀O. D is false: butanal, CH₃CH₂CH₂CHO, is C₄H₈O, with two hydrogens fewer. So A, B and C are correct.

Question 55

Chemistry · Organic Chemistry · Standard

Ethene reacts with water, in the presence of an acid catalyst, to give ethanol: CH₂=CH₂ + H₂O → CH₃CH₂OH. Which of the following terms describe this reaction? Select all correct answers.

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Answer: A

A is true: H and OH add across the C=C double bond and no other product forms, so this is an addition (a hydration). B is false: in a substitution one atom or group replaces another, which does not happen here. C is false: elimination is the reverse, removing water from ethanol to give ethene. D is false: a condensation joins two molecules with the loss of a small molecule such as water, whereas here water is taken up. So only A is correct.

Question 56

Chemistry · Organic Chemistry · Challenging

Which of the following molecules contain a chiral (asymmetric) carbon atom? Select all correct answers.

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Answer: A, C

A chiral carbon carries four different substituents. A is true: C2 of butan-2-ol carries H, OH, CH₃ and C₂H₅. B is false: C2 of propan-2-ol carries two identical CH₃ groups. C is true: the α-carbon of alanine carries H, NH₂, COOH and CH₃. D is false: the α-carbon of glycine carries two hydrogens, so glycine is the one achiral proteinogenic amino acid. So A and C are correct.

Question 57

Chemistry · Biochemistry · Foundation

Which pair of monosaccharides makes up the disaccharide sucrose? Select all correct answers.

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Answer: B

A is false: glucose and galactose make lactose, milk sugar. B is true: sucrose, table sugar, is glucose joined to fructose. C is false: two glucose units make maltose (or, with a different bond, cellobiose). D is false: fructose and galactose do not make sucrose. So only B is correct.

Question 58

Chemistry · Biochemistry · Standard

Which of the following bonds join neighbouring amino acids in the primary structure of a protein? Select all correct answers.

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Answer: D

A is false: ester bonds join fatty acids to glycerol in fats. B is false: glycosidic bonds join monosaccharides in carbohydrates. C is false: phosphodiester bonds join nucleotides in nucleic acids. D is true: the peptide (amide) bond −CO−NH− forms between the carboxyl group of one amino acid and the amino group of the next. So only D is correct.

Question 59

Chemistry · Biochemistry · Standard

Which of the following vitamins are fat-soluble? Select all correct answers.

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Answer: C

A is false: vitamin C (ascorbic acid) is water-soluble. B is false: vitamin B₁₂ (cobalamin), like all B vitamins, is water-soluble. C is true: vitamin D is one of the fat-soluble vitamins A, D, E and K. D is false: vitamin B₁ (thiamine) is water-soluble. So only C is correct.

Question 60

Chemistry · Biochemistry · Challenging

What is the net number of ATP molecules gained in glycolysis from one molecule of glucose? Select all correct answers.

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Answer: B

Glycolysis uses 2 ATP in its first stage and makes 4 ATP by substrate-level phosphorylation in its second, a net gain of 2. A is false: one ATP is not the net yield. B is true. C is false: 4 is the gross yield, before the 2 ATP invested are subtracted. D is false: 8 does not correspond to glycolysis alone. So only B is correct.

Question 61

Logic · Numerical Reasoning · Foundation

What is the next number in the series 3, 7, 15, 31, 63, ...?

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Answer: C

Each term is double the previous one plus 1: 3 × 2 + 1 = 7, 7 × 2 + 1 = 15, and so on, so 63 × 2 + 1 = 127. The differences 4, 8, 16, 32 confirm it: the next difference is 64, and 63 + 64 = 127. 126 is the tempting answer if you only double and forget the + 1.

Question 62

Logic · Numerical Reasoning · Standard

What is the next number in the series 2, 3, 5, 9, 17, ...?

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Answer: A

The differences are 1, 2, 4, 8, doubling each time, so the next difference is 16 and 17 + 16 = 33. (Equivalently, each term is double the previous one minus 1.) 25 is what you get by repeating the last difference of 8 instead of doubling it.

Question 63

Logic · Numerical Reasoning · Standard

One tap fills a tank in 6 hours and a second tap fills the same tank in 3 hours. If both taps are opened together on the empty tank, how long does it take to fill?

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Answer: D

In one hour the first tap fills 1/6 of the tank and the second 1/3 = 2/6, so together they fill 3/6 = 1/2 of the tank per hour, and the whole tank takes 2 hours. 4.5 hours, the average of the two times, is the tempting distractor, but two taps together must be faster than the faster tap alone, so the answer has to be under 3 hours.

Question 64

Logic · Numerical Reasoning · Standard

A jacket costs €100. Its price is raised by 20%, and the new price is then reduced by 20%. What is the final price?

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Answer: B

After the rise the price is 100 × 1.2 = €120. A 20% reduction of €120 is €24, so the final price is 120 − 24 = €96 (overall 1.2 × 0.8 = 0.96). €100 is the trap: the two 20% changes do not cancel, because the reduction is taken from a larger amount.

Question 65

Logic · Numerical Reasoning · Challenging

Anna is three times as old as Ben. In 10 years' time she will be twice as old as he will be. How old is Anna now?

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Answer: B

Let Ben be b, so Anna is 3b. In 10 years: 3b + 10 = 2(b + 10), so 3b + 10 = 2b + 20 and b = 10. Anna is 30 now. Check: in 10 years they will be 40 and 20, and 40 is twice 20. 40 is the tempting slip, since it is Anna's age in 10 years, not now.

Question 66

Logic · Numerical Reasoning · Challenging

What is the next number in the series 1, 4, 2, 8, 3, 12, 4, ...?

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Answer: A

Two series alternate. The 1st, 3rd, 5th and 7th terms are 1, 2, 3, 4 and the 2nd, 4th and 6th terms are 4, 8, 12, going up by 4 (each is four times the term before it). The missing term is the 8th, so it belongs to the second series: 12 + 4 = 16. 5 is the tempting answer, but it would continue the first series, whose next term is the 9th.

Question 67

Logic · Verbal and Abstract Logic · Foundation

PAINTER is to BRUSH as SURGEON is to:

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Answer: B

A brush is the hand tool a painter works with; the scalpel is the hand tool a surgeon works with. A hospital is where a surgeon works, a patient is who is treated, and an operation is what is done, so none is the tool. Operation is the tempting option because it is so closely linked with a surgeon, but the matching link to a painter would be a painting, not a brush.

Question 68

Logic · Verbal and Abstract Logic · Standard

All nurses at a hospital are vaccinated. Some vaccinated people are volunteers. Which of the following must be true?

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Answer: C

Every nurse at the hospital is vaccinated, so a nurse who is also a volunteer is certainly vaccinated. The tempting option A does not follow: the vaccinated volunteers could all be people who are not nurses, so there may be no nurse volunteers at all. B reverses the second premise, which says only that some vaccinated people volunteer. D is not supported either: nothing rules out a nurse volunteering.

Question 69

Logic · Verbal and Abstract Logic · Standard

If it rains, the match is cancelled. The match was not cancelled. What follows?

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Answer: D

"If it rains, the match is cancelled" is equivalent to its contrapositive, "If the match is not cancelled, it did not rain". The match was not cancelled, so it did not rain. Option C is the tempting one, but it describes the opposite case: had we been told the match was cancelled, nothing could be concluded about rain, since it might have been cancelled for another reason. Nothing in the statements mentions where the match was played.

Question 70

Logic · Verbal and Abstract Logic · Standard

Five runners, P, Q, R, S and T, finish a race with no ties. P finishes before Q. Q finishes before S. R finishes immediately after S. T finishes last. Who finishes third?

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Answer: C

T is 5th, so P, Q, R and S take places 1 to 4. P is before Q and Q is before S, so S is at least 3rd. S cannot be 4th, because R must come immediately after S and 5th belongs to T. So S is 3rd, R 4th, and P and Q, in that order, take 1st and 2nd. The order P, Q, S, R, T is the only one possible. R is the tempting answer if you place S second, but that leaves no room for both P and Q ahead of it.

Question 71

Logic · Verbal and Abstract Logic · Challenging

Only students who passed the exam may enrol on the course. Marta has enrolled on the course. Luca passed the exam. Which of the following must be true?

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Answer: A

"Only those who passed may enrol" means enrolling requires a pass: if someone enrolled, they passed. Marta enrolled, so she passed. The tempting error is to read the rule backwards, as "everyone who passed enrols" or "may enrol": passing is necessary, not sufficient, so nothing follows about Luca, and D is that same reversal stated generally.

Question 72

Logic · Verbal and Abstract Logic · Foundation

Which statement is the negation of "All the patients were discharged"?

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Answer: B

A statement "all are X" is false as soon as one is not X, so its negation is "at least one is not X". "No patient was discharged" is the tempting answer, but it is a much stronger claim: if nine of ten patients went home, both the original statement and "no patient was discharged" would be false. C is compatible with the original statement, and D claims more than the negation does.

Question 73

Logic · Spatial and Pattern Reasoning · Foundation

Which letter comes next in the sequence A, C, F, J, O, ...? (Use the 26-letter English alphabet.)

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Answer: C

By position in the alphabet the letters are 1, 3, 6, 10, 15: the gaps are 2, 3, 4, 5, so the next gap is 6 and 15 + 6 = 21, which is U. T (20) is the tempting answer if the gap is kept at 5.

Question 74

Logic · Spatial and Pattern Reasoning · Standard

A net of a cube is a row of four squares numbered 1, 2, 3 and 4 from left to right, with square 5 attached above square 2 and square 6 attached below square 2. When the net is folded into a cube, which face is opposite face 1?

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Answer: D

When a row of four squares folds round into a loop, each square ends up opposite the one two places along: 1 opposite 3 and 2 opposite 4. Squares 5 and 6 fold up and down from the same square, so they become the top and bottom, opposite each other. Face 1 is therefore opposite face 3. 4 is the tempting answer because it is at the far end of the row, but faces 1 and 4 meet along an edge when the loop closes.

Question 75

Logic · Spatial and Pattern Reasoning · Challenging

A die whose opposite faces add up to 7 sits on a table with 1 on top and 2 on the face towards you. It is rolled away from you three times, each time tipping over its far bottom edge onto the next face. Which number is on top after the third roll?

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Answer: D

At the start: top 1, front 2, bottom 6, back 5. Rolling away, the front face comes up to the top, the top goes to the back, the back goes to the bottom and the bottom comes to the front. Roll 1: top 2, front 6, bottom 5, back 1. Roll 2: top 6, front 5, bottom 1, back 2. Roll 3: top 5, front 1, bottom 2, back 6. So 5 is on top. 6 is the tempting answer if you stop after two rolls, and 2 if you count only one.

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