1
MCQ (Single Correct Answer)

AIPMT 2012 Prelims

Equimolar solutions of the following substances were prepared separately. Which one of these will record the highest pH value ?
A
BaCl2
B
AlCl3
C
LiCl
D
BeCl2

Explanation

All of the given salts have same anion i.e., Cl which on hydrolysis gives HCl which is a strong acid.

Now, among the salts which have cation that gives a strongest base on hydrolysis of salt have the highest pH value. As Ba form Ba(OH)2 which is a stronger base thus, it results in the highest pH value.
2
MCQ (Single Correct Answer)

AIPMT 2012 Prelims

pH of a saturated solution of Ba(OH)2 is 12. The value of solubility product (Ksp) of Ba(OH)2 is
A
3.3 $$ \times $$ 10$$-$$7
B
5.0 $$ \times $$ 10$$-$$7
C
4.0 $$ \times $$ 10$$-$$6
D
5.0$$ \times $$ 10$$-$$6

Explanation

Ba(OH)2 Ba2+ + 2OH
At equilibrium x 2x


pH = – log[H+]

12 = – log [H+]

$$ \Rightarrow $$ [H+] = 10–12

As, [H+][OH ] = 10–14

10–12 [OH ] = 10–14

$$ \Rightarrow $$ [OH ] = 10–2

As [OH ] = 2x = 10–2 then x = 5.0 × 10–3

Now, Ksp = [Ba2+][OH ]2

Ksp = (5 × 10–3) (10–2)2 = 5.0 × 10–7
3
MCQ (Single Correct Answer)

AIPMT 2011 Mains

In qualitative analysis, the metals of group I can be separated from other ions by precipitating them as chloride salts. A solution initially contains Ag+ and pb2+ at a concentration of 0.10 M. Aqueous HCl is added to this solution until the Cl$$-$$ concentration is 0.10 M. What will the concentrations of Ag+ and Pb2+ be at equilibrium ?

(Ksp for AgCl = 1.8 $$ \times $$ 10$$-$$10, Ksp for PbCl2 = 1.7 $$ \times $$ 10$$-$$5)
A
[Ag+] = 1.8 $$ \times $$ 10$$-$$7 M, [Pb2+] = 1.7 $$ \times $$ 10$$-$$6 M
B
[Ag+] = 1.8 $$ \times $$ 10$$-$$11 M, [Pb2+] = 8.5 $$ \times $$ 10$$-$$5 M
C
[Ag+] = 1.8 $$ \times $$ 10$$-$$9 M, [Pb2+] = 1.7 $$ \times $$ 10$$-$$3 M
D
[Ag+] = 1.8 $$ \times $$ 10$$-$$11 M, [Pb2+] = 1.7 $$ \times $$ 10$$-$$4 M

Explanation

Ksp[AgCl] = [Ag+][Cl-]

$$ \Rightarrow $$ [Ag+] = $${{1.8 \times {{10}^{ - 10}}} \over {{{10}^{ - 1}}}}$$ = 1.8 $$ \times $$ 10$$-$$9 M

Ksp[PbCl2] = [Pb2+][Cl-]2

$$ \Rightarrow $$ [Pb2+] = $${{1.7 \times {{10}^{ - 5}}} \over {{{10}^{ - 1}} \times {{10}^{ - 1}}}}$$ = 1.7 $$ \times $$ 10$$-$$3 M
4
MCQ (Single Correct Answer)

AIPMT 2011 Prelims

Which of the following is least likely to behave as Lewis base?
A
H2O
B
NH3
C
BF3
D
OH$$-$$

Explanation

The species which have a lone pair of electrons to donate or a negative charge on it can act as a Lewis base. Here, N atom in NH3 and O atom in H2O have lone pair of electrons available for donation. In OH the negative charge on it results in to behave it as a Lewis base. But BF3 is an electron deficient species thus, it is least likely to behave as Lewis base.

EXAM MAP

Joint Entrance Examination

JEE Advanced JEE Main

Medical

NEET

Graduate Aptitude Test in Engineering

GATE CE GATE ECE GATE ME GATE IN GATE EE GATE CSE GATE PI