﻿ The pH of an aqueous solution of CH3COONa of concentration C

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# 1.The pH of an aqueous solution of CH3COONa of concentration C(M) is given by:7 - 1/2 pKa - 1/2 log C 1/2 pKw + 1/2 pKb + 1/2 log C 1/2 pKw - 1/2 pKb - 1/2 log C 1/2 pKw - pKa + 1/2 log C

D.

1/2 pKw - pKa + 1/2 log C

CH3COONa + H2$⇌$  +

As sodium acetate is a salt of weak acid and strong base, in the hydrolysis of sodium acetate the pH is given by;

pH = 1/2 pKw + 1/2 pKa + 1/2 log C

2.

If the equilibrium constants of the following equilibria,

SO2 + 1/2O2 $\to$ SO3 and 2SO3 $\to$ 2SO2 + O2

are given by K1 and K2 respectively, which of the following relations is correct?

• K2 = (1/K1)2

• K1 = (1/K3)3

• K2 = (1/K1)

• K2 = (K1)2

3.

The energy of an electron in first Bohr orbit of H-atom is-13.6 eV. The possible energy value of electron in the excited state of Li2+ is:

• - 122.4 eV

• 30.6 eV

• - 30.6 eV

• 13.6 eV

4.

The amount of the heat released when 20 mL 0.5 M NaOH is mixed with 100 ml 0.1 M HCl is x kJ. The heat of neutralisation is:

• - 100 x kJ/mol

• - 50 x kJ/mol

• + 100 x kJ/mol

• + 50 x kJ/mol

5.

Which one of the following has the lowest ionisation energy?

• 1s2 , 2s2 , 2p6

• 1s2 , 2s2 , 2p6 , 3s1

• 1s2 , 2s2 , 2p5

• 1s2 , 2s2 , 2p3

6.

2 g of metal carbonate is neutralised completely by 100 mL of 0.1 N HCI. The equivalent weight of metal carbonate is:

• 50

• 100

• 150

• 200

7.

An electric current is passed through an aqueous solution of a mixture of alanine (isoelectric point 6.0), glutamic acid (3.2) and arginine (10.7) buffered at pH 6. What is the fate of the three acids?

• Glutamic acid migrates to anode at pH 6. Arginine is present as a cation and migrates to the cathode. Alanine in a dipolar ion remains uniformly distributed in solution

• Glutamic acid migrates to cathode and others remain uniformly distributed in solution

• All three remain uniformly distributed in solution

• All three move to cathode

8.

The representation of the ground state electronic configuration of He by box-diagram as
 $↑↑$

is wrong because it violates:

• Heisenberg's uncertainty principle

• Bohr's quantization theory of angular momenta

• Pauli exclusion principle

• Hund's rule

9.

The electronic transitions from n = 2 to n = 1 will produce shortest wavelength in (where n = principal quantum state)

• Li2+

• He+

• H

• H+

10.

In the following electron-dot structure calculate the formal charge from left to right nitrogen atom; $\stackrel{\mathbf{.}\mathbf{.}}{\underset{\mathbf{.}\mathbf{.}}{\mathrm{N}}}=\mathrm{N}=\stackrel{\mathbf{.}\mathbf{.}}{\underset{\mathbf{.}\mathbf{.}}{\mathrm{N}}}$ :

• -1 , -1 , +1

• -1 , +1 , -1

• +1 , -1 , -1

• +1 , -1 , +1