Which of the following pairs will not produce dihydrogen gas ?

1. Cu + HCl (dil.)

2. Fe + H₂SO₄

3. Mg + steam

4. Na + alcohol

When zeolites (hydrated sodium aluminum silicate) is treated with hard water, the sodium ions are exchanged with:

1. H⁺ ion

2. Ca²⁺ ion

3. ${\mathrm{SO}}_4^{2-}$ ion

4. OH^- ion

 The formation of atomic hydrogen from molecular hydrogen will be favoured most at ?

1. High temperature and high pressure

2. Low temperature and low pressure

3. High temperature and low pressure

4. Low temperature and high pressure

The bleaching properties of H₂O₂ are due to its: 

1. Reducing properties

2. Oxidising properties

3. Unstable nature

4. Acidic nature

The metal that does not displace hydrogen from an acid is:

1. Hg

2. Zn

3. Al

4. Ca

The catalyst used in Bosch process of manufacture of H₂ is:

1. finely divided Ni

2. V₂O₅

3. Pd

4. Fe₂O₃ + Cr₂O₃

An aqueous solution of hydrogen peroxide is:

1. alkaline

2. neutral

3. strongly acidic

4. weakly acidic

The correct statement among the following regarding perhydrol is -

1. It is 30% H₂O₂ or 100 vol. H₂O₂

2. Its molarity is 8.8 M

3. It is used as an antiseptic and a germicide

4. All of the above

On bubbling CO₂ through a solution of barium peroxide in water:

1. O₂ is formed

2. H₂CO₃ is formed

3. H₂O₂ is formed

4. H₂ is formed

Temporary hardness is caused due to the presence of:

1. CaSO₄

2. CaCl₂

3. CaCO₃

4. Ca(HCO₃)₂