The correct order of \(\mathrm{C-O}\) bond length among \(\mathrm{CO},\mathrm{CO}_3^{2-},\) and \(\mathrm{CO_2}\) is :

1. \(\mathrm{CO}_2<\mathrm{CO}_3^{2-}<\mathrm{CO} \)
2. \(\mathrm{CO}<\mathrm{CO}_3^{2-}<\mathrm{CO}_2 \)
3. \(\mathrm{CO}_3^{2-}<\mathrm{CO}_2<\mathrm{CO} \)
4. \(\mathrm{CO}<\mathrm{CO}_2<\mathrm{CO}_3^{2-}\)

Which of the following is not a correct statement?

Which of the following is not isostructural with SiCl₄?

1. \(SCl_4\)

2. \(SO_4^{2-}\)

3. \(PO_4^{3-}\)

4. \(NH_4^+\)
$$

Which of the following diatomic molecular species has only $\mathrm{\pi }$ bonds according to Molecular Orbital Theory?

1.  Be₂

2.  O₂

3.  N₂

4.  C₂

The number of sigma ($\mathrm{\sigma }$) and pi ($\mathrm{\pi }$) bonds in pent-2-en-4-yne is:

1. 13 $\mathrm{\sigma }$ bonds and no $\mathrm{\pi }$ bond

2. 10 $\mathrm{\sigma }$ bonds and 3 $\mathrm{\pi }$ bonds

3. 8 $\mathrm{\sigma }$ bonds and 5 $\mathrm{\pi }$ bonds

4. 11 $\mathrm{\sigma }$ bonds and 2 $\mathrm{\pi }$ bonds

The correct structure of tribromo octoxide is:

Which of the molecule is not hypovalent but complete octet :

1. AlCl₃                   

2. AlBr₃

3. AlF₃                     

4. BF₃

A molecule that has a complete octet is:

 1. BeCl₂(dimer)       

 2. BeH₂(dimer)

 3. BeH₂(s)               

 4. BeCl₂(s)

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.

According to Born-Haber's cycle, the enthalpy of the formation of ionic compounds can be determined. The formation of NaCl involves the following steps :

(I) \(Na(s)\xrightarrow[Energy \ of \ sublimation]{S} \ Na(g)\)     

(II) \(Na(g)\xrightarrow[Ionisation \ potential]{I} \ Na^{+}(g) \ + \ e^{-}\)

(III) \(Cl_{2}(g)\xrightarrow[Bond \ dissociation \ energy]{D} \ 2Cl(g)\)

(IV) \(Cl(g) \ + e^{-}\xrightarrow[Electron \ affinity \ energy]{E} \ Cl^{-}(g)\)

 (V) \(Cl^{-}(g) \ + Na^{+}(g)\xrightarrow[Lattice \ energy \ energy]{U} \ NaCl(s)\)

The enthalpy of formation of NaCl will be :

1. $∆{\mathrm{H}}_{\mathrm{f}}=\mathrm{S}+\mathrm{I}-\frac{\mathrm{D}}{2}-\mathrm{E}-\mathrm{U}$

2. $∆{\mathrm{H}}_{\mathrm{f}}=\mathrm{S}+\mathrm{I}+\frac{\mathrm{D}}{2}-\mathrm{E}-\mathrm{U}$

3. $∆{\mathrm{H}}_{\mathrm{f}}=-\mathrm{S}-\mathrm{I}-\mathrm{D}+\frac{E}{2}+\mathrm{U}$

4. $∆{\mathrm{H}}_{\mathrm{f}}=-\mathrm{S}-\mathrm{I}-\mathrm{D}-\frac{E}{2}-\mathrm{U}$