Solution of Section A

i) B ii) A iii) B iv) C v) D vi) D

Solution of Section B

Q3

a)

i) Zinc powder + nitric acid / (option ii) (1)

b) Larger surface area, so more exposed, hence greater chances of successful collisions (3)

c) Any two:

Increasing the temperature , adding catalyst , Increasing the pressure , Increasing the concentration (2)

Q4a. exothermic. This is because the forward reaction has a negative heat change, indicating that heat is released.

bi. The amounts of A, B and AB2 are constant (equilibrium) but the forward and backward reactions are still taking place (dynamic).

bii. amount of AB2 increases

c. Rate is faster. At higher temperature, the molecules have more kinetic energy. More molecules possess energy greater than the required minimum energy for a reaction to take place. Furthermore, they collide more frequently with one another. Hence, the rate of reaction increases.

Q6 (a) Zn(s) + 2HCl(aq) → ZnCl2(aq) + H2(g) [2]1 mark for correctly balanced equation ;1 mark for correct state symbols (dependent on all formulae being correct)

(b) (i) gas escapes / hydrogen escapes / gas given off / hydrogen given off / gas released /hydrogen released / gas produced / gas evolved / hydrogen is a gas ; [1]NOT: hydrogen produced without qualification. ALLOW: ecf from wrong gas inpart (a)(ii) downwards curve starting at the same point as the original curve but displayed tothe left (at least at first) ; [1]Line ends at the same mass as the original ; [1]NOT: curve dipping markedly below the horizontal section and then goingupwards to meet it

(c) (acid) particles in dilute acid are less crowded / there are fewer particles (of acid) ina given volume / the particles (of acid) are further apart ; [1]ALLOW: concentration of HCl particles is lowerALLOW: molecules / ions in place of particlesALLOW: reverse argument e.g. particles in concentrated acid are more crowded /there are more particles (of acid) in a given volume etcIGNORE: there are fewer molecules unqualified / there is more water there are moremoles in a given volume.fewer collisions (in dilute acid) / less chance of collisions (in dilute acid) / frequency ofcollisions lower (in dilute acid) ; [1]ALLOW: reverse argument e.g. more collisions (in concentrated acid) / morechance of collisions (in concentrated acid) ;IGNORE: effective (collisions)

(d) more particles exposed / large(r) surface area ; [1]ALLOW: atoms / ions in place of particlesmore collisions / greater chance of collisions / particles collide more often / greaterfrequency of collisions ; [1]IGNORE: effective (collisions)