The reaction H₂S + H₂O₂ ⟶ S + 2H₂O manifests

Acidic nature of H₂O₂
Alkaline nature of H₂O₂
Oxidising action of H₂O₂
Reducing action of H₂O₂

Solution

H₂S is oxidised to S by H₂O₂.

Which of the following statements do not define the characteristic property of water “Water is a universal solvent”

It can dissolve maximum number of compounds
It has very low dielectric constant
It has high liquid range
None of these

Solution

Water has high dielectric constant i.e., 78.39 C²/Nm²,high liquid range and can dissolve maximum number of compounds. That is why it is used as universal solvent.

Which of the following is not true?

D₂O freezes at lower temperature than H₂O
Reaction between H₂ and Cl₂ is much faster than D₂ and Cl₂
Ordinary water gets electrolysed more rapidly than D₂O
Bond dissociation energy of D₂ is greater than H₂

Solution

D₂O actually has higher freezing point (3.8°C) than water H₂O (0°C)

Chemical A is used for water softening to remove temporary hardness. A reacts with sodium carbonate to generate caustic soda. When CO₂ is bubbled through a solution of A, it turns cloudy. What is the chemical formula of A.

CaCO₃
CaO
Ca(OH)₂
Ca(HCO₃)₂

Solution

Water possesses a high dielectric constant, therefore :

it always contains ions
it is a universal solvent
can dissolve covalent compounds
can conduct electricity

Solution

Due to high dielectric constant, water acts as a good solvent therefore it is also called a universal solvent.

What is formed when calcium carbide reacts with heavy water?

C₂D₂
CaD₂
Ca₂D₂O
CD₂

Solution

CaC₂ + 2D₂O ⟶ C₂D₂ + Ca(OD)₂

The boiling point of water is exceptionally high because

there is covalent bond between H and O
water molecule is linear
water molecules associate due to hydrogen bonding
water molecule is not linear

Solution

The high boiling point of water is due to H-bonding.

The alum used for purifying water is

ferric alum
chrome alum
potash alum
ammonium alum

Solution

Potash alum is used for purifying water.

The percentage by weight of hydrogen in H₂O₂ is

5.88
6.25
25
50

Solution

% hydrogen in H₂O₂ = \(\frac{2}{34}\) × = 5.88%

When zeolite (hydrated sodium aluminium silicate) is treated with hard water the sodium ions are exchanged with

H⁺ ions
Ca²⁺ ions
\(SO_{4}^{2-}\) ions
OH^-ions

Solution

Na zeolite + CaCl₂ ⟶ Ca zeolite + 2NaCl

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