Which of the following compounds has the lowest melting point?

1. $CaB{r}_2$

2. $Ca{l}_2$

3. $Ca{F}_2$

4. $CaC{l}_2$

The dissociation equilibrium of a gas AB₂ can be represented as-
 
The degree of dissociation is 'x' and is small compared to 1. The expression relating the degree of dissociation (x) with equilibrium constant K_P and total pressure p is:

1. $\left(2k_p/p\right)$

2. ${\left(2k_p/p\right)}^{1/3}$

3. ${\left(2k_p/p\right)}^{1/2}$

4. $(k_p/p)$

A buffer solution is prepared in which the concentration of NH₃ is 0.30 M and the concentration of NH₄⁺ IS 0.20 M. If the equilibrium constant, K_b for NH₃ equals 1.8 ×10^-5. What is the pH of this solution?

1. 9.43

2. 11.72

3. 8.73

4. 9.08

If a gas expands at a constant temperature, it indicates that: 

1. kinetic energy of molecules decreases

2. pressure of the gas increases

3. Kinetic energy of molecules remains the same

4. number of the molecules of gas increase

If n = 6, the correct sequence for the filling of electrons will be:

1.  ns → (n-1)d → (n-2)f → np

2.  ns → (n-2)f → np → (n-1)d

3.  ns → np → (n-1)d → (n-2)f

4.  ns → (n-2)f → (n-1)d → np

Which of the following is least likely to behave as Lewis base?

1. $N{H}_3$

2. $B{F}_3$

3. $O{H}^{-}$

4. $H_{2}O$

In DNA, the complementary bases are:

1. Adenine and thymine; guanine and cytosine

2.  Adenine and thymine; guanine and uracil

3.  Adenine and guanine ; thymine and cytosine

4. Uracil and adenine, cytosine and guanine

Which one of the following does not undergo an iodoform reaction?

1. Secondary butyl alcohol

2. So-propyl alcohol

3. Diethyl ketone

4. Ethyl alcohol

Percentage of free space in a body centre cubic unit cell is:

1. 30%

2. 32%

3. 34%

4. 28%