The role of an electrolyte in the  preparation of H₂ by electrolytic method is:

The most abundant isotope of hydrogen is-

1. Tritium

2. Deuterium

3. Protium

4. Para-hydrogen

The products obtained on the completion of the following reactions (i) and (ii) respectively are :

1. A = CO, and H₂ ; B = Na₂ZnO₂
2. A  = CO₂ ; B = Na₄ZnO₄
3. A = CH₃CH₂CH₂OH ; B=  ZnO
4. None of the above

The correct statement among the following regarding hydrogen is–

1. It can form a bond in +1 as well as –1 oxidation state

2. It is always collected at the cathode

3. It has a very low ionization potential

4. It has the same electronegativity as halogens

When substance A reacts with water, it produces a combustible gas B and a solution of substances 'C' in water. When another substance 'D' reacts with this solution of C, it produces the same gas 'B' on warming but 'D' can produce gas 'B' on reaction with dilute sulphuric acid at room temperature. 'A' imparts a deep golden yellow colour to a smokeless flame of a bunsen burner. A, B, C and D respectively are -

1. $\mathrm{Na},$ ${\mathrm{H}}_2,$ $\mathrm{NaOH},$ $\mathrm{Zn}$                              

2. $\mathrm{K},$ ${\mathrm{H}}_2,$ $\mathrm{KOH},$ $\mathrm{Al}$

3. $\mathrm{Ca},$ ${\mathrm{H}}_2,$ $\mathrm{Ca}{\left(\mathrm{OH}\right)}_2,$ $\mathrm{Sn}$                           

4. ${\mathrm{CaC}}_2,$ ${\mathrm{C}}_2{\mathrm{H}}_2,$ $\mathrm{Ca}{\left(\mathrm{OH}\right)}_2,$ $\mathrm{Fe}$

Ice melts at a temperature lower than its usual melting point when the pressure is increased. This is because-

1. Ice has less density than water

2. Pressure generates heat

3. The chemical bonds break under pressure

4. Ice is not a true solid

The first ionization energy value $\left(\mathrm{kJ}\right)$ ${\mathrm{mol}}^{-1}$ for $\mathrm{H},$ $\mathrm{Li},$ $\mathrm{F},$ $\mathrm{and}$ $\mathrm{Na}$ 

is given below but not in a correct order

$1681,$ $520,$ $1312,$ $495.$

The ionization energy value of H would be -

1. 1681                                 

2. 1312

3. 520                                   

4. 485

Dihydrogen gas cannot be prepared with-

1. Cu + HCl (dil.)

2. Fe + H₂SO₄

3. Mg + steam

4. Na + alcohol

A compound among the following that has hydrogen in the atomic state is –

1. Metallic hydrides                           

2. Ionic hydrides

3. Molecular hydrides                       

4. Water

Hydrogen adsorbed on palladium is known as:

1. Atomic H

2. Nascent H

3. Occluded H

4. Heavy H