Fill in the Blanks
Q.1. The conjugate base of in aqueous solution is ........... (1982 - 1 Mark)
Ans.
Solution. ; Conjugate base = Acid – H+
∴ Conjugate base of
Q.2. An element which can exist as a positive ion in acidic solution and also as a negative ion in basic solution is said to be ............... . (1984 - 1 Mark)
Ans. amphoteric
Solution. amphoteric ; because amphoteric substances show properties of both acids and basic
Q.3. For a given reversible reaction at a fixed temperature, equilibrium constants Kp and Kc are related by........ (1994 - 1 Mark)
Ans. Kp = Kc (RT)Δn
Solution. Kp = Kc (RT)Δn ;
Here Δn = No. of moles of gaseous products – no. of moles of gaseous reactants
R = gas constant, and T = absolute temperature.
Q.4. A ten - fold increase in pressure on the reaction , at equilibrium results in .... in KP. (1996 - 1 Mark)
Ans. no change
Solution. no change; (Kp of an equilibrium reaction is independent of the pressure of the system.)
Q.5. In the reaction I–+I2 → I3- , the Lewis acid is ........... . (1997 - 1 Mark)
Ans. I2
Solution. I2. ∵ electron acceptors are Lewis acids.
True/False
Q.1. Aluminium chloride (AlCl3) is a Lewis acid because it can donate electrons. (1982 - 1 Mark)
Ans. F
Solution. False : AlCl3 is a Lewis acid (although they do not have a proton, aprotic) because it accepts electrons (octet being incomplete).
Q.2. If equilibrium constant for the reaction is K, then for the backward reaction the equilibrium constant is 1/K. (1984 - 1 Mark)
Ans. F
Solution. False :
Q.3. When a liquid and its vapour are at equilibrium and the pressure is suddenly decreased, cooling occurs. (1984 - 1 Mark)
Ans. T
Solution. True : Lower the pressure, lower will be boiling point. More liquid will vapourise and temperature decreases.
Q.4. Solubility of sodium hydroxide increases with increase in temperature. (1985 - ½ Mark)
Ans. F
Solution. TIPS/Formulae : Dissolution of NaOH is exothermic.
False : When a solute like NaOH is added to a solvent exothermic dissolution takes place. An increase in temperature always favour endothermic process. So solutes having exothermic dissolution shows a decrease in their solubility with temperature
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