How many possible resonance forms exist for the nitrate ion, \(\text{NO}_3^-\)​?

1.	One	2.	Two
3.	Three	4.	Four

Which of the following molecule will have all equal $\mathrm{X}—\mathrm{F}$ bond length? (where X= central atom)

$$\begin{gathered} \left(\mathrm{a}\right) {\mathrm{SOCl}}_2{\mathrm{F}}_2 \\ \left(\mathrm{b}\right) {\mathrm{SeF}}_4 \\ \left(\mathrm{c}\right) {\mathrm{PBr}}_2{\mathrm{F}}_3 \\ \left(\mathrm{d}\right) {\mathrm{IF}}_7 \end{gathered}$$

Which of the following fact is directly explained by the statement 'oxygen is a smaller atom than sulpher'?

(1) $H_{2}O$ boils at a much higher tempreture than $H_{2}S$

(2) $H_{2}S$ undergoes intermolecure hydrogen bonding

(3) $H_{2}O$ is liquid and $H_{2}S$ is gas at room tempreture 

(4) S$—$H bond is longer than O$—$H bond

Among given species identify the isostructural pairs:

(1) $\left[N{F}_{3 } and B{F}_3\right]$

(2) $\left[B{F_4}^{-} and N{H_4}^{+}\right]$

(3) $\left[BC{l}_3 and BrC{l}_3\right]$

(4) $\left[N{H}_3 and N{O_3}^{-}\right]$

Consider the following information (X=F or Cl)

Molecule     P-X(axial)       P-X(Equitorial) 

                 bond length     bond length

PF_{5                     a                        b}

PF₄CH_{3            c                        d}

PF₃(CH₃)_{2       e                       f}

PCl_{5                   g                      h}

According to information choose the incorrect order of bond length :

(1)g>a>d>b                                             

(2) g>e>f>b

(3) f>d>a>b                                             

(4) c>f>d>b

In which of the following cases $\mathrm{C}—\mathrm{C}$ bond length will be highest?

(1) ${\mathrm{CH}}_3—{\mathrm{CF}}_3$                               (2) ${\mathrm{FCH}}_2—{\mathrm{CH}}_2\mathrm{F}$

(3) ${\mathrm{F}}_2\mathrm{CH}-{\mathrm{F}}_2\mathrm{CH}$                            (4) ${\mathrm{CF}}_3—{\mathrm{CF}}_3$

The ratio of $\mathrm{\sigma } / \mathrm{\pi } \mathrm{bond}$ in tetracyano ethylene is: 

(1) 2:1

(2) 1:1

(3) 1:2 

(4) none of these 

Which of the following statement is correct in the context of the allene molecules, $C_3{H}_4$?

1. The central carbon is Sp hybridized

2. The terminal carbon atoms are $s{p}^2$ hybridized

3. The planes containing the $C{H}_2$ groups are  mutually perpendicular to permit the formations of two separate $\pi$ - bonds 

4. All are correct 

Select the incorrect statement about ${\mathrm{N}}_2{\mathrm{F}}_{4 }\mathrm{and} {\mathrm{N}}_2{\mathrm{H}}_4$:

(i) In${\mathrm{N}}_2{\mathrm{F}}_4$, d-orbitals are contracted by electronegative fluorine atoms, but d-orbitals contaraction is not possible by H-atom in ${\mathrm{N}}_2{\mathrm{H}}_4$

(ii) The N-N bond energy in ${\mathrm{N}}_2{\mathrm{F}}_4$ is lesser than N-N bond energy in ${\mathrm{N}}_2{\mathrm{H}}_4$

(iii) The N-N bond length in ${\mathrm{N}}_2{\mathrm{F}}_4$ is more than that in ${\mathrm{N}}_2{\mathrm{H}}_4$

(iv) The N-N bond length in ${\mathrm{N}}_2{\mathrm{F}}_4$ is less than that in ${\mathrm{N}}_2{\mathrm{H}}_4$

Choose the correct code:

(a) (i),(ii) and (iii)                                        (b) (i) and (iii)

(c) (ii) and (iv)                                            (d) (ii) and (iii)

The shape of $\mathrm{Xe}{{\mathrm{F}}_3}^{+}$ is: