The 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

H₂O₂ restores the colour of old lead paintings by:

1. Converting PbO₂ to Pb

2. Oxidising PbS to PbSO₄

3. Converting PbCO₃ to Pb

4. Oxidizing PbSO₃ to PbSO₄

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

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

The oxidation states of the most electronegative element in the products of the reaction between ${\mathrm{BaO}}_2$ with dil. ${\mathrm{H}}_2{\mathrm{SO}}_4$ are–

1. 0, and –1                                   

2. –1, and –2

3. –2, and 0                                     

4. –2, and + 1

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

A compound that has both polar and non-polar bonds is  –

1. ${\mathrm{NH}}_4\mathrm{Cl}$                                    

2. $\mathrm{HCN}$

3. ${\mathrm{H}}_2{\mathrm{O}}_2$                                     

4. ${\mathrm{CH}}_4$

The colour of hydrogen is –

1. Blue                           

2. Yellow

3. Orange                       

4. No colour

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

The incorrect statement among the following  regarding reaction of  ${\mathrm{H}}_2{\mathrm{O}}_2$ is -

1.  ${\mathrm{S}}^{-2}$ $\to$ $\mathrm{S}$ (acidic medium)

2.  $\mathrm{Pb}$ $\to$ ${\mathrm{PbSO}}_4$

3.  ${\mathrm{Fe}}^{3+}$ $\to$ ${\mathrm{Fe}}^{2+}$ (acidic medium)

4.  $\mathrm{KI}$ $\to$ ${\mathrm{I}}_2$