An incorrect statement among the following regarding hydrogen is:
 

1.	Hydrogen never acts as a cation in ionic salts.
2.	Hydronium ion, H3O+ exists freely in a solution.
3.	Dihydrogen does not act as a reducing agent.
4.	Hydrogen has three isotopes of which protium is the most common.

The ease of adsorption of the hydrated alkali metal ions on ion-exchange resins follows the order:

1. $L{i}^{+}<K^{+}<N{a}^{+}<R{b}^{+}$

2. $R{b}^{+}<K^{+}<N{a}^{+}<L{i}^{+}$

3. $K^{+}<N{a}^{+}<R{b}^{+}<L{i}^{+}$

4. $N{a}^{+}<L{i}^{+}<K^{+}<R{b}^{+}$

The method used to remove the temporary hardness of water is-

1. Synthetic resins method

2. Calgon's method

3. Clark's method

4. Ion-exchange method

The ease of adsorption of the hydrated alkali metal ions on an ion-exchange resins

follows the order:

1. Li⁺<K⁺<Na⁺<Rb⁺

2. Rb⁺<K⁺<Na⁺<Li⁺

3. K⁺<Na⁺<Rb⁺<Li⁺

4. Na⁺<Li⁺<K⁺<Rb⁺

In acidic medium, H₂O₂ changes ${\mathrm{Cr}}_2{\mathrm{O}}_7^{2-}$ to CrO₅ which has two (-O-O-) bonds. Oxidation

state of Cr in CrO₅ is

1. +5

2. +3

3. +6

4. -10

(I) ${\mathrm{H}}_2{\mathrm{O}}_2+{\mathrm{O}}_3 \stackrel{ }{\to }{\mathrm{H}}_2\mathrm{O} + 2{\mathrm{O}}_2$

(II) ${\mathrm{H}}_2{\mathrm{O}}_2 + {\mathrm{Ag}}_2\mathrm{O} \stackrel{ }{\to }2\mathrm{Ag} + {\mathrm{H}}_2\mathrm{O} + {\mathrm{O}}_2$

Role of hydrogen peroxide in the above reactions is respectively

1. oxidising in (I) and reducing in (II)

2. reducing in (I) and oxidising in (II)

3. reducing in (I) and  (II)

4. oxidising in(I) and (II)

Match the following and identify the correct option