You're on a roll — i) To determine the rate of reaction at 12 minutes: Step 1: Locate the point on the curve corresponding to $12$ minutes on the time (x-axis). Step 2: Draw a tangent to the curve at this specific point. Step 3: Calculate the gradient (slope) of this tangent. The gradient, $\frac{\Delta \text{Total volume of oxygen}}{\Delta \text{Time}}$, represents the rate of reaction at $12$ minutes. ii) The production of oxygen in region $\text{A}_1\text{B}_1$ is faster than in region $\text{B}_1\text{C}_1$. Explanation: In region $\text{A}_1\text{B}_1$, the concentration of reactants is higher, leading to a greater frequency of effective collisions between reactant particles and thus a faster rate of reaction. As the reaction proceeds into region $\text{B}_1\text{C}_1$, the concentration of reactants decreases, resulting in fewer effective collisions and a slower rate of oxygen production. iii) The equation for the decomposition of hydrogen peroxide is: $$ 2\text{H}_2\text{O}_2(aq) \to 2\text{H}_2\text{O}(l) + \text{O}_2(g) $$ c) i) A major source of nitrogen gas in the Haber process is air. Got more? Send 'em!