Which of the following elements does not show allotropy?

1. Nitrogen

2. Bismuth

3. Antimony

4. Arsenic

The maximum covalency of nitrogen is:

Which of the following statements is wrong?

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:

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:

The oxidation state of the central atom in the anion of the compound ${\mathrm{NaH}}_2{\mathrm{PO}}_2$ will be-

1. +3

2. +5

3. +1

4. -3

Which of the following is not tetrahedral in shape?

$1. {\mathrm{NH}}_4^{+}$
$2. {\mathrm{SiCl}}_4$
$3. {\mathrm{SF}}_4$
$4. {\mathrm{SO}}_4^{2-}$

Which of the following are peroxoacids of sulphur?