Chemistry MCQs for NEET — Practice Questions with Answers

The equilibrium constant Kp for the reaction 2NOBr(g) ⇌ 2NO(g) + Br2 is given by Kp = [NO]2[Br2]/[NOBr]2. At equilibrium, PBr2 = P/9, where P is the total pressure. Since there are 3 moles of gas on the product side and 2 moles on the reactant side, Kp/P = (P/9)/(P(2/3))2 = 1/81.

(b) K_c = [Ca²⁺][F^-]² ;

          if [Ca²⁺] = 4x[Ca²⁺];

           To have K_c  constant [F^-] should be [F^-]/2.

(d) Common ion effect is noticed only for weak electrolyte dissociation H₂SO₄ is strong electrolyte.

(c) Since, OH^- are generated from weak acid (H₂O), a weak acid (like CO₂) should be used to remove it because of strong acid (HCl) reverse the reaction. KOH increases the concentration of OH^-, thus again shifts the reaction in backward side. CO₂  combines with OH^- to give carbonate which is easily removed. SO₂ reacts with water to give strong acid, so it cannot be used.

(d) According to law of mass action, the rate of a reaction is directly proportional to the product of active masses or molar concentrations of reactions.

                     A+B$\to$product

Rate of reaction $\propto$[A][B]

(a) More is the acidic character, lesser is basic character of conjugate base.

(b) Boiling temperature increases with increase in pressure.

(a) HCl is acid. Its pH will be <7.

(c) In 0.1 M NaCl, the solubility of AgCl is minimum due to the phenomenon of common ion effect.

(c) The highest pH refers to the basic solution containing OH^- ions. Therefore, the basic salt releasing more OH^- ions on hydrolysis will give highest pH in water.

Only the salt of strong base and weak acid would release more OH- ions on hydrolysis. Among the given salts, Na₂CO₃ corresponding to the basic salt as it is formed by the neutralisation of NaOH [strong base] and H₂CO₃ [weak acid].

            C${\mathrm{O}}_3^{2-}$ + H₂O $\rightleftharpoons$ HC${\mathrm{O}}_3^{-}$ + OH^-