1.1 A reaction in which products can be converted back to reactants is described as: A) Heterogeneous B) Homogeneous C) Reversible D) Spontaneous 1.2 Which ONE of the following reaction conditions applies to esterification? A) Heat reaction mixture mildly over a water bath B) Apply heat directly to the reaction mixture C) Add concentrated hydrochloric acid to the reaction mixture D) None of the above 1.3 What NAME is given to the process of breaking down long chain hydrocarbons into more shorter chains? A) Hydrogenation B) Cracking C) Dehydrogenation D) Polymerisation 1.4 Which ONE of the following changes will increase the rate of production of H₂(g) in the reaction: Mg(s) + H₂SO₄(aq) → MgSO₄(aq) + H₂(g) A) Increase in pressure by decreasing the volume B) Add water to the reaction mixture C) Increase the volume of the H₂SO₄(aq) D) Increase the concentration of the H₂SO₄(aq) 1.5 Consider the reversible reaction: 3 Y₂(g) ⇌ 2 Y₃(g) ΔH = -80 kJ If the activation energy for the reverse reaction is 180 kJ, then the activation energy for the forward reaction is … A) -80 kJ - NSC Physical Sciences - Question 1 - 2016 - Paper 2

The correct answer is A) Heat reaction mixture mildly over a water bath. This method ensures controlled temperature, which is essential for successful esterification.

The correct answer is B) Cracking. This process involves breaking larger hydrocarbon molecules into smaller, more useful ones, typically in the presence of heat and a catalyst.

The correct answer is D) Increase the concentration of the H₂SO₄(aq). This will increase the frequency of effective collisions between reactant molecules, thereby enhancing the rate of reaction.

If the activation energy for the reverse reaction is 180 kJ, then the activation energy for the forward reaction is 80 kJ (as the overall energy change is the difference in activation energies).

The correct choice is B) dilute solution of a weak acid. Given the concentration and the dissociation constant, HX is classified as a weak acid.

Using the dilution formula, C₁V₁ = C₂V₂, we find that the volume must be 100 cm³.

The correct answer is A) The solution turns pink. The addition of hydrochloric acid shifts the equilibrium, causing a color change.

The correct answer is D) The concentration of H₃O⁺ increases. As temperature rises, the ionization of water increases, leading to more H₃O⁺ and OH⁻ ions.