In which of the following processes nitrogen is oxidised?

1. ${\mathrm{NH}}_4^{+}$ $\to$N₂

2. ${\mathrm{NO}}_3^{-} \to$NO

3. NO₂ $\to$${\mathrm{NO}}_2^{-}$

4. ${\mathrm{NO}}_3^{-}$$\to$N${\mathrm{H}}_4^{+}$ 

In the preparation of chlorine from HCl; MnO₂ acts as:

1. Reducing agent

2. Oxidising agent

3. Catalytic agent

4. Dehydrating agent

Oxidation number of carbon in C₃O₂, Mg₂C₃ are respectively:

1. -4/3, +4/3 

2. +4/3, -4/3

3. -2/3, +2/3

4. -2/3, +4/3

The oxidation number and covalency of sulphur in the sulphur molecule (S₈) are respectively:

1. 0, and 2

2. +6, and 8

3. 0, and 8

4. +6, and 2

Hypochlorite disproportionate to give

1. Cl^- and Cl${\mathrm{O}}_4^{-}$

2. Cl${\mathrm{O}}_4^{-}$ and Cl${\mathrm{O}}_3^{-}$

3. Cl${\mathrm{O}}_3^{-}$ and Cl^-

4. Cl${\mathrm{O}}_2^{-}$ and Cl^-

When Cl₂ is converted into Cl^- & Cl${\mathrm{O}}_3^{-}$ then n-factor of Cl₂ will be:

1. 3/5

2. 5/3

3. 7/2

4. 2

MnO₂ + 4HCl $\to$MnCl₂+2H₂O+Cl₂, the equivalent wt. of HCl will be (M$\equiv$Mol wt of HCl)

1. M

2. M/2

3. 2M

4. M/4

In the following unbalanced reaction

A²⁺ + B³⁺ $\to$A⁴⁺ + B

The total number of e^- transferred during reaction is:

1. 2

2. 3

3. 6

4. 8

In the reaction

xBrO_3^- + yCr⁺³ + zH₂O $\to$Br₂ + CrO_4^-2 + H⁺

the coefficients x,y,z are respectively ?

1. 6, 10, 11

2. 6, 10, 20

3. 6, 8, 22

4. 6, 10, 22

In the reaction

Al + Fe₃O₄ $\to$Al₂O₃ + Fe

total number of electrons transferred during reaction are:-

1. 6

2. 8

3. 8/3

4. 24