AS & A Level Chemistry (9701) — May–June 2025, Paper 42
9 questions · every question answerable online with instant point-by-point AI marking against the official mark scheme.
Start with Question 1 →The thermal decomposition of Group 2 nitrates can be represented by the equation: M(NO3)2(s) → MO(s) + 2NO2(g) + ½O2(g) (i) Write the equation for the thermal decomposition of…
Answer this question and get it marked →CoSO4 solution is added to excess NaOH solution. (i) State the colour of the precipitate formed when NaOH is first added to CoSO4. (ii) Write an ionic equation for the reaction of…
Answer this question and get it marked →Define the term entropy.
Answer this question and get it marked →H2O2 oxidises I⁻ ions in acidic solution. H2O2 + 2I⁻ + 2H⁺ → I2 + 2H2O The initial rate of reaction was measured for different initial concentrations of H2O2 and I⁻. The results…
Answer this question and get it marked →HClO is a weak acid. HClO ⇌ H⁺ + ClO⁻ Write the expression for Ka for this equilibrium and identify the conjugate acid–base pairs.
Answer this question and get it marked →Benzene reacts with HNO3 and H2SO4 to form nitrobenzene. (i) Write an equation to show how the electrophile is formed from HNO3 and H2SO4. (ii) Complete the mechanism for the…
Answer this question and get it marked →Define the term enantiomers.
Answer this question and get it marked →Compound A is isopropyl propanoate, CH3CH2COOCH(CH3)2. The proton (1H) NMR spectrum of compound A shows peaks at δ 1.10, 1.50, 2.85 and 3.75 ppm (approximately). (i) State why TMS…
Answer this question and get it marked →Serine (ser) and lysine (lys) are amino acids. Serine: H2N−CH(CH2OH)−COOH Lysine: H2N−(CH2)4−CH(NH2)−COOH (i) Draw the structure of the dipeptide ser-lys. (ii) Define the term…
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