The ${\mathrm{BF}}_3$ is a planar molecule whereas ${\mathrm{NF}}_3$ is pyramidal because:

1. $\mathrm{B}-\mathrm{F}$ bond is more polar than $\mathrm{N}-\mathrm{F}$ bond.

2. Boron atom is bigger than nitrogen atom.

3. Nitrogen is more electronegative than boron.

4. ${\mathrm{BF}}_3$ has no lone pair but ${\mathrm{NF}}_3$ has a lone pair of electrons.

The correct order of acidic strength is :

1. ${\mathrm{Cl}}_2{\mathrm{O}}_7>{\mathrm{SO}}_2>{\mathrm{P}}_4{\mathrm{O}}_{10}$                   

2. ${\mathrm{CO}}_2>{\mathrm{N}}_2{\mathrm{O}}_5>{\mathrm{SO}}_3$

3. ${\mathrm{Na}}_2\mathrm{O}>\mathrm{MgO}>{\mathrm{Al}}_2{\mathrm{O}}_3$                   

4. ${\mathrm{K}}_2\mathrm{O}>\mathrm{CaO}>\mathrm{MgO}$

A diatomic molecule has a dipole moment of 1.2 D. If its bond length is equal to 10 ^-10 m , then the fraction of an electronic charge on each atom will be:

1. 42%
2. 52%
3. 37%
4. 25%

 When two atoms combine to form a molecule, energy is: 

Compounds that have a maximum value of lattice energy among the following, is:
 

A Compound with maximum ionic character is formed from:

Most covalent compound among the following is :

The correct order of covalent bond character among
LiCl, BeCl₂, BCl₃ and CCl₄, is:

1. LiCl < BeCl₂ > BCl₃ > CCl₄

2. LiCl > BeCl₂ < BCl₃ < CCl₄

3. LiCl < BeCl₂ < BCl₃ < CCl₄

4. LiCl > BeCl₂ > BCl₃ > CCl₄

The molecule having the smallest bond angle is-

Which of the following conversions demonstrates an increase in bond order and a change in magnetic behaviour?

1. $NO\to N{O}^{+}$                                 

2. $O_2\to O_2+$

3. $N_2\to N_2^{+}$                                   

4. $C_2\to C_2^{+}$