Which of the following elements does not show allotropy?

1. Nitrogen

2. Bismuth

3. Antimony

4. Arsenic

The maximum covalency of nitrogen is:

1. 3
2. 5
3. 4
4. 6

Which of the following statements is wrong?

1. Single N—N bond is stronger than a single P—P bond.

2. ${\mathrm{PH}}_3$ can act as a ligand in the formation of coordination compound with transition elements.

3. ${\mathrm{NO}}_2$ is paramagnetic in nature.

4. Covalency of nitrogen in ${\mathrm{N}}_2{\mathrm{O}}_5$ is four.

A brown ring is formed in the ring test for ${\mathrm{NO}}_3^{-}$ ion. It is due to the formation of:

1. [Fe(H₂O)₅(NO)]²⁺
2. FeSO₄.NO₂ 
3. [Fe(H₂O)₄ (NO)₂]²⁺
4. FeSO₄. HNO₃

Elements of group-15 form compounds in +5 oxidation state. However, bismuth forms only one well-characterized compound in +5 oxidation state. The compound is-

$1. {\mathrm{Bi}}_2{\mathrm{O}}_5$
$2. {\mathrm{BiF}}_5$
$3. {\mathrm{BiCl}}_5$
$4. {\mathrm{Bi}}_2{\mathrm{S}}_5$

On heating ammonium dichromate and barium azide separately we get:

1.  ${\mathrm{N}}_2$ in both cases

2.  ${\mathrm{N}}_2$ with ammonium dichromate and $\mathrm{NO}$ with barium azide

3.  ${\mathrm{N}}_2\mathrm{O}$ with ammonium dichromate and ${\mathrm{N}}_2$ with barium azide

4.  ${\mathrm{N}}_2\mathrm{O}$ with ammonium dichromate and ${\mathrm{NO}}_2$ with barium azide

In the preparation of ${\mathrm{HNO}}_3$, we get $\mathrm{NO}$ gas by catalytic oxidation of ammonia. The moles of NO produced by the oxidation of two moles of ${\mathrm{NH}}_3$ will be ......... .

1.  2

2.  3

3.  4

4.  6

In solid-state, PCl₅ exists as: 

Which of the following is correct for P₄ molecule of white phosphorus?

a. It has 6 lone pairs of electrons

b. It has six P — P single bonds

c. It has three P — P single bonds

d. It has four lone pairs of electrons

Choose the correct option

1. (a, b)
2. (b, c)
3. (c, d)
4. (b, d)

Which of the following statements are correct?

1. (a, b)
2. (b, c)
3. (c, d)
4. (a, d)