Buffer solutions have constant acidity and alkalinity because
1. these give unionised acid or base or base on reaction with added acid or alkali
2. acids and alkalies in these solutions are shielded from attack by other ions
3. they have large excess of H⁺ or OH^- ions
4. they have fixed value of pH

 

The molecule that is least likely to behave as Lewis base is: 

1. NH₃

2. BF₃

3. OH^-

4. H₂O

K_c and K_p are not equal for a reaction given below:

1. 2NO(g) $\rightleftharpoons$N₂(g) + O₂(g)

2. SO₂(g) + NO₂(g) $\rightleftharpoons$SO₃(g) + NO(g)

3. H₂(g) + I₂(g) $\rightleftharpoons$2HI(g)

4. 2C(s) + O₂(g) $\rightleftharpoons$2CO₂(g)

Which one of the following molecular hydrides acts as a Lewis acid?

1. NH₃         

2. H₂O         

3. B₂H₆           

4. CH₄

Which of the following molecules acts as a Lewis acid ?

1. (CH₃)₃B

2. (CH₃)₂O

3. (CH₃)₃P

4. (CH₃)₃N

The ionisation constant of ammonium hydroxide is 1.77 x 10^-5 at 298 K. Hydrolysis constant of ammonium chloride is

1. 5.65 x 10^-10

2. 6.50 x 10^-12

3. 5.65 x 10^-13

4. 5.65 x 10^-12

The oxide that is not expected to react with sodium hydroxide is : 

1. B₂O₃           

2. CaO

3. SiO₂             

4. BeO

The dissociation constants for acetic acid and HCN at 25$°$C are 1.5 xl0^-5 and 4.5 xl0^-10,

respectively. The equilibrium constant for the equilibrium,

CN^- + CH₃COOH  =    HCN + CH₃COO^-   would be

1. 3.0 x 10⁵

2. 3.0 x 10^-5

3. 3.0x10^-4

4. 3.0 x 10⁴

Equal volumes of three acid solutions of pH 3, 4 and 5 are mixed in a vessel. What will be

the H⁺ ion concentration in the mixture?

1. 1.11 x 10^-4 M             

2. 3.7 x 10^-4 M

3. 3.7 x 10^-3  M             

4. 1.11 x 10^-3 M

The value of equilibrium constant of the reaction HI (g) $\rightleftharpoons$ $\frac{1}{2}$ H₂(g) + $\frac{1}{2}$ I₂(g) is 8.0. The equilibrium constant of the reaction

H₂(g) + I₂(g) $\rightleftharpoons$2HI(g) will be

$$\begin{gathered} 1. \frac{1}{16} \\ 2. \frac{1}{64} \\ 3. 16 \\ 4. \frac{1}{8} \end{gathered}$$