Question

Which of the following statements is incorrect?

• A. In equilibrium mixture of ice and water kept in perfectly insulated flask, mass of ice and water does not change with time.
• B. The intensity of red colour increases when oxalic acid is added to a solution containing iron (III) nitrate and potassium thiocyanate.
• C. On addition of catalyst, the equilibrium constant value is not affected.
• D. Equilibrium constant for a reaction with negative value decreases as the temperature increases.

Answer 1

Answer: (B)

The intensity of red colour increases when oxalic acid is added to a solution containing iron (III) nitrate and potassium thiocyanate.

Answer 2

:

When oxalic acid is added, it reacts with $\mathrm { Fe } ^ { 3 + }$ ions to form stable complex ion $\left[ \mathrm { Fe } \left( \mathrm { C } _ { 2 } \mathrm { O } _ { 4 } \right) _ { 3 } \right] ^ { 3 - }$ , thus decreasing the conc. of free $[ \mathrm { Fe } ( \mathrm { SCN } ) ] ^ { 2 + }$decreases, so the intensity of red colour decreases.