Class 11th

At a particular temperature and atmospheric pressure, the solid and liquid phases of a pure substance can exist in equilibrium. Which of the following term defines this temperature?

(i) Normal melting point

(ii) Equilibrium temperature

(iii) Boiling point

(iv) Freezing point

When the first element of the periodic table is treated with dioxygen, it gives a compound whose solid state floats on its liquid state. This compound has an ability to act as an acid as well as a base. What products will be formed when this compound undergoes auto ionization?

In the following questions two or more options may be correct.

For the reaction N₂O₄ (g) ⇌2NO₂ (g), the value of K is 50 at 400 K and 1700 at 500 K. Which of the following options is correct?

(i) The reaction is endothermic

(ii) The reaction is exothermic

(iii) If NO₂ (g) and N₂O₄ (g) are mixed at 400 K at partial pressures 20 bar and 2 bar respectively, more N₂O₄ (g) will be formed.

(iv) The entropy of the system increases.

Explain why HCl is a gas and HF is a liquid.

In which of the following reactions, the equilibrium remains unaffected on addition of small amount of argon at constant volume?

(i) H₂ (g) + I₂ (g) ⇌ 2HI (g)

(ii) PCl₅ (g) ⇌  PCl₃ (g) + Cl₂ (g)

(iii) N₂ (g) + 3H₂ (g) ⇌
2NH₃ (g)

(iv) The equilibrium will remain unaffected in all the three cases.

Dihydrogen reacts with dioxygen (O₂) to form water. Write the name and formula of the product when the isotope of hydrogen which has one proton and one neutron in its nucleus is treated with oxygen. Will the reactivity of both the isotopes be the same towards oxygen? Justify your answer.

At 500 K, equilibrium constant, K_c , for the following reaction is 5.

$\frac{1}{2}{\mathbf{H}}_2$ (g) + $\frac{1}{2}{\mathbf{I}}_2$  (g) ⇌ HI (g)

What would be the equilibrium constant K_c for the reaction

2HI(g) ⇌ H₂ (g) + I₂ (g)

(i) 04

(ii) 4

(iii) 25

(iv) 5

Melting point, enthalpy of vaporization and viscosity data of H₂O and D₂O is given below:

On the basis of this data explain in which of these liquids intermolecular forces are stronger?

What will be the correct order of vapour pressure of water, acetone and ether at 30°C. Given that among these compounds, water has maximum boiling point and ether has minimum boiling point?

(i) Water < ether < acetone

(ii) Water < acetone < ether

(iii) Ether < acetone < water

(iv) Acetone < ether < water

On increasing the pressure, in which direction will the gas phase reaction proceed to re-establish equilibrium, is predicted by applying the Le Chatelier's principle. Consider the reaction.

N₂ (g) + 3H₂ (g) ⇌2NH₃ (g)

Which of the following is correct, if the total pressure at which the equilibrium is established, is increased without changing the temperature?

(i) K will remain same

(ii) K will decrease

(iii) K will increase

(iv) K will increase initially and decrease when pressure is very high