Acids, Bases and Salts - 1 (Class - IX)

This is the correct option. Oxides of aluminium and zinc metals show basic as well as acidic behaviour and are called amphoteric oxides. Their oxides react with acids as well as bases to form salt and water.

 Na₂O is a basic oxide.

Carbon is a non-metal. It will form an acidic oxide. For example, CO₂ combines with water to form carbonic acid (H₂CO₃).

NaOH is the strongest base among the given options. It will produce the largest number of OH^– ions in water.

According to Arrhenius concept of acids and bases, “An acid is a substance which is capable of furnishing H⁺ ions in aqueous solution and base is a substance which is capable of furnishing OH^– ions”. According to this, NH₃ is not a base.

It does not explain the existence of hydrogen ion in water.

Oxides of potassium and magnesium turn litmus solution blue because potassium and magnesium are metals. Metals form basic oxides which turn litmus solution blue.

Oxides of metals are basic in nature and on reaction with water, they produce bases. Sodium, magnesium and copper are metals. Therefore, Na₂O, MgO and CuO are basic oxides.
Sulphur is a non-metal and oxides of non-metals are either acidic or neutral. Therefore, SO₂ is an acidic oxide as it reacts with water to produce an acid.

This is the correct option. Ammonium chloride is a salt of a strong hydrochloric acid and a weak ammonium hydroxide base.

Concentration of hydrogen ion [H⁺] in
0.1 M HNO₃ = 0.1 M
0.1 M CH₃COOH = Less than 0.1 M because it is a weaker acid.
0.1 M HCL = 0.1 M
0.1 M H₂SO₄ = 0.2 M [because it ionises as H₂SO₄ ⇌ 2H⁺ + SO₄^2-]
[H⁺] = 2 × [H₂SO₄] = 2 × 0.1 = 0.2 M
Hence, 0.1 M H₂SO₄ is the strongest acid.

All these are weak bases and [OH^–] in each of these compounds is given as follows:
0.01 M NH₄OH = 0.01 M
0.01 M Al(OH)₃ = 0.03 M
0.01 M Ca(OH)₂ = 0.02 M
0.01 M NH₂OH = 0.01 M

Yes, it is correct. Here, the basic radical is Cl^-, which is present in both the salts.

Acids give hydrogen gas along with a salt when they react with a metal. Here, a metal carbonate reacts with an acid to give carbon dioxide and water.

This is the correct option. The nature of sodium carbonate solution is basic. The nature of ammonium chloride solution is acidic. The nature of sodium chloride solution is neutral.

This is the correct option. Sodium carbonate is used as washing soda and for softening hard water.