The number of $\mathrm{\pi }$ bonds and $\mathrm{\sigma }$ bonds in the following structure is :

The total number of possible resonance forms for the nitrate ion, ($\mathrm{N}{{\mathrm{O}}_3}^{-}$) is: 

The most preferred structure among the following with the lowest energy for SO₃ is: 

1.		2.
3.		4.

An incorrect statement regarding resonating structures is : 

${\mathrm{H}}_3{\mathrm{PO}}_3$ can be represented by structures 1 and 2 shown below. 

These two structures cannot be taken as the canonical forms of the resonance hybrid, because  : 

1. The positions of the atoms have changed.

2. The positions of the atoms are constant.

3. H₃PO₃ does not show resonance.

4. Two hydrogen atoms are missing.

The correct order of 'S$—$O' bond length is:

Which of the following has a maximum 'Cl-O' bond order?

1. ${\mathrm{ClO}}_3^{-}$

2. ${\mathrm{ClO}}_3$

3. ${\mathrm{ClO}}_2$

4. ${\mathrm{ClO}}_2^{-}$

Mg₂C₃ reacts with water forming propyne ${\mathrm{C}}_3^{4-}$ . The number of sigma and pie bonds in \(C_{3}^{4-}\)is-  

1. Two sigma and two pi bonds.             

2. Three sigma and one pi bonds.           

3. Two sigma and one pi bonds.          

4. Two sigma and three pi bonds.