Question

The variation of $K$ and ${K_f}$ as well as ${K_b}$​ with temperature shows the following effects:
(i) For endothermic reactions $K$ increases and ${K_f}$ as well as ${K_b}$ ​ also increases with temperature.
(ii) For endothermic reaction $K$ decreases and ${K_f}$ as well as ${K_b}$ also decreases with temperature.
(iii) For an exothermic reaction $K$ decreases and ${K_f}$ as well as ${K_b}$ ​ both increases with temperature.
(iv) For an exothermic reaction $K$ increases and ${K_f}$ as well as ${K_b}$ decreases with temperature.
(v) For an exothermic reaction $K$ decreases and ${K_f}$ ​ as well as ${K_b}$ ​ both decreases with temperature.

A. (i), (iii)
B. (iii), (iv)
C. (ii), (iii)
D. (ii), (iii), (v)

Answer 1

Hint:As we know ${E_a}$ is always positive hence, the rate constant increases with the temperature. Knowledge of exothermic reaction and endothermic reaction is must for this question.

Complete step-by-step answer:
As we all know,
${E_a}$ is always positive hence, the rate constant increases with the temperature.
\[\Delta H\] is negative, \[\dfrac{{{K_f}}}{{{K_b}}}\] or \[{K_c}\]​ decreases with temperature.
\[\Delta H\] is positive, \[\dfrac{{{K_f}}}{{{K_b}}}\]​​ or \[{K_c}\]​ increases with temperature.

Additional Information:
Endothermic reactions are actually the chemical reactions in which the reactants absorb heat energy from its surroundings to produce products. These reactions actually lower the temperature of their nearby area, hence creating a cooling effect.
 Exothermic reactions are actually the reactions or processes that are used to release energy, generally in the form of heat or light. In an exothermic reaction, the energy released due to the total energy of the products is lesser than the total energy of the reactants.
Every chemical equilibrium can be distinguished by an equilibrium constant, also known as ${K_{eq}}$.. The ${K_{eq}}$ and ${K_P}$ expressions are generated as the amounts of products which are divided by the amounts of reactants; each amount (whether a concentration or a pressure) is raised to the power of its coefficient in the balanced chemical equation.
By increasing the temperature it decreases the value of the equilibrium constant. The forward reaction is actually the endothermic, and increasing the temperature actually increases the value of the equilibrium constant. Thereby, according to Le Chatelier's Principle the position of equilibrium will get positioned to the left.

Hence, Option A. is correct.

Note:By observing the hint and the options, answers can be easily determined. Also as we know ${E_a}$ is always positive hence, the rate constant increases with the temperature.