The equilibrium constant for a reaction,$A + B \rightleftharpoons C + D$ is $1 \times 10^{-2}$ at $298 \ K$ and is $2$ at $273 \ K$. The chemical process resulting in the formation of $C$ and $D$ is

$2B_{(g)} + 2C_{(g)} \rightleftharpoons 3A_{(g)} + \text{heat}$; necessary conditions to obtain high amount of $A$ are

The oxidation of $SO_2$ to $SO_3$ by $O_2$ is an exothermic reaction: $2SO_2(g) + O_2(g) \rightleftharpoons 2SO_3(g) + \text{Heat}$. The yield of $SO_3$ will increase if:

Change in volume of the system does not alter the number of moles in which of the following equilibrium?

Assertion : $A$ catalyst does not alter the equilibrium constant of a reaction.
Reason : The catalyst forms a complex with the reactants and provides an alternate path with lower energy of activation for the reaction; the forward and the backward reactions are affected to the same extent.

Write the effect of concentration change on equilibrium and explain it with a suitable example.