Explanation:
The endothermic reaction is favoured when the temperature increases. The concentration of products increases at t=10 mins; therefore, the forward reaction must be endothermic.
Increasing the volume decreases the pressure and causes the side with more moles of gas to be favoured. The concentration of reactants increases at t=15 mins; therefore, the reactants must have more moles of gas than the products.

Explanation:
The ratio of SO3:SO2:O2 is 2:2:1. Therefore, half the number of moles of oxygen would be produced compared to SO2

Explanation:
$)$.
If $\Delta G$ is positive, ln(K) must be negative. ln(K) is negative for values smaller than 1.
A positive $\Delta G$ value indicates that the reaction is not spontaneous. Therefore, the equilibrium concentrations of the reactants are larger than the ones of the products; the equilibrium constant is less than 1.

Explanation:
D has the steepest gradient when a tangent is drawn.

Therefore, 0.5 moles of H2require 0.167 moles of N2 to completely react. There are $s$ of N2NX2 available so N2 is the reactant in excess.

Explanation:
Students should be aware of the definition of frequency factor. However, questions on this topic are somewhat uncommon, and students could confuse this concept with the idea that molecules capable of successful collision lie above Ea in a Boltzmann distribution (leading them to select option D). The difficulty level is therefore at the higher end of the “easy” range.

Explanation:
All graphs are [A] vs time.
A linear plot of [A] vs time represents a zero order reaction, B and D represent first order reactions (B represents [A] as a product and is therefore increasing).
C is a second order plot of [A] vs time and has a steeper initial rate (slope) when compared to first order reactions.

Explanation:
The rate expression can only be determined experimentally.

Explanation:
The peaks represent transition states where energy is at its highest. This graph shows a multi-step mechanism where Y is an intermediate species between R and P. Catalysts lower the activation energy which is the difference between R and X.

Explanation:
Rate is directly proportional to the concentration of $M$ as it is first order. As the concentration of $M$ has been multiplied by 1.5, the rate (0.5 s−1) must also be multiplied by 1.5.

Explanation:

The correct balanced equation is:

2LiOH + H2SO4 → Li2SO4 + 2H2O.

2+1+1+2 = 6

Explanation:
Graph D shows that rate is proportional to [A]2.
A and B are concentration-time graphs. C is a first order rate-concentration graph as they are directly proportional

Explanation:
The equilibrium shifts to favor the endothermic reaction (forward) when the temperature is increased to resist that change (Le Chatelier’s principle).
Temperature is the only factor that changes the value of the equilibrium constant.

Explanation:
The $ln(2)$ term appears because k1 is double k2, and the factor of 1000 appears in the denominator to convert J mol−1to kJ mol−1.
Option B is almost correct, but the temperature terms 1/298 and 1/308 would need to be swapped to give a positive value for the activation energy.
The question is in the “hard” or “very hard” category since students must be able to identify the correct terms in the question for use in the equation, rearrange the equation correctly, and also perform a unit conversion.

Explanation:
Using trials 1 and 2, as the concentration of I^− doubles, the rate also doubles. Rate and [I−] are therefore, directly proportional with an order of 1.

Explanation:
Four factors that can increase the rate of a chemical reaction are: increasing the temperature of the reaction, adding a catalyst, increasing the concentration of the reactants and decreasing the solid particle size of the reactants.

Explanation:
The y-intercept = $lnA$ so must be larger for reaction 1.
The gradient (slope) is equal to −Ea/R so, must be shallower (less negative) for reaction 1.
The question is in the “hard” category as students must know how to interpret an Arrhenius plot (or correctly interpret the given equation) and compare two reactions graphically.

Explanation:

Kc is written as the concentrations of the products divided by the concentrations of the reactants each raised to the power of the coefficient in the balanced equation.

Explanation:
Q>Kc, therefore the backward reaction will be favored as the system approaches dynamic equilibrium.
The backward reaction is endothermic, so the temperature will decrease.
There are more moles of gas on the left and so pressure increases. NO2 is red-brown and so the gas mixture will get darker.