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

Explanation​:
Units for $k$ are determined by dividing the units of rate by the units of the concentrations raised to their respective powers.
For a 3rd order reaction, k=mol dm−3 s−1/mol3 dm−9 = mol−2 dm6 s−1.

Explanation​:
A catalyst provides an alternative pathway for the reaction lowering the activation energy. It affects both the forward and reverse reaction rates equally. The position of equilibrium will not change.

Explanation:​
Kc>1, and so lies towards the right with the yellow product at equilibrium; the color would therefore be a pale green due to more yellow than blue.
When an acid is added, it reacts with the OH− reducing its concentration. Equilibrium shifts to the right to oppose that change.

Kc only changes with temperature. Adding an alkali would increase the OH− concentration and therefore the equilibrium would shift to the left to oppose that change. Kc​ again would remain the same as it is only affected by temperature.

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 rate constant increases with increasing A and decreases with increasing Ea​.
This question is on the lower end of the medium-difficulty category as students should be familiar with the effect of these variables on $k$, and are given the equation for assistance if needed.

Explanation​:
The coefficients of all species in the equation are halved which results in Kc​ being square rooted.
Kc​ = [NOCl2]2/[NO]2[Cl2]​

Explanation​:

The theoretical yield is the maximum amount of product that will be formed if the limiting reagent is consumed completely.

Explanation:​
The number of molecules remains constant. Temperature only changes the particles’ kinetic energy; when temperature increases, the kinetic energy of the particles also increases.

Explanation:
The balanced chemical equation is 2C3H7OH(l)+9 O2(g)→6 CO2(g)+8 H2O(l). The sum of the coefficients is $25$.

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:​
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:​
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:​
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​:
Using the Arrhenius equation k = Ae−Ea/RT, a linear relationship will be created by graphing ln k vs. 1/T​

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.

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.