Acids, Bases and Salts – Maharashtra Board Class 7 Solutions for General Science

Acids, Bases and Salts – Maharashtra Board Class 7 Solutions for General Science (English Medium)

MathematicsGeneral ScienceMaharashtra Board Solutions

Solution 1.a:

	Acids	Bases
1.	Acids are sour in taste.	Bases have a sharp astringent taste.
2.	Acids turn blue litmus paper red.	Bases turn red litmus paper blue.
3.	They are not soapy to touch.	They are soapy to touch.
4.	Acids contain H+ ions.	Basis contains OH– ions.
5.	Examples: Hydrochloric acid, sulphuric acid, acetic acid, tamarind, buttermilk	Examples: Sodium hydroxide, calcium hydroxide, baking soda, lime, soap

Solution 1.b:

An indicator reacts with an acid or a base. Salt is a neutral substance, so an indicator will not react with it.

Solution 1.c:

Salt and water are formed as a result of a neutralisation reaction.

Solution 1.d:

A base is a substance which has sharp and astringent taste and is soapy to touch. A base which dissolves in water is called an alkali. All alkalis are bases, but all bases are not alkalis.

Solution 2:

• The main constituent of an acid is H.
• The main constituent of a base is OH.
• Tartaric acid is a weak acid.
• To get acidic salts, strong acids are used.

Solution 3:

Group ‘A’	Group ‘B’
(a) Tamarind	3. Tartaric acid
(b) Yoghurt	4. Lactic acid
(c) Lemon	2. Citric acid
(d) Acetic acid	1. Vinegar

Solution 4:

• True
• False. Common salt is neutral.
• True
• False. Salts are formed by the neutralisation reaction between acids and bases.
• True

Solution 5:

• Na₂CO₃ is a base, whereas HNO₃, H₂SO₄ and HCl are acids.
• H₂O is neutral, whereas MgO, CaO and Na₂O are metal oxides.
• CH₃COOH is an acid, whereas NaHCO₃, NaOH and NH₄OH are bases.
• C₁₂H₂₂O₁₁ is a sugar, whereas NaCl, KCl and CuSO₄ are salts.
• CH₃COOH is a weak acid, whereas HCl, H₂SO₄ and HNO₃ are strong acids.

Solution 6:

1. Acidic substances: HCl, H₂SO₄, HNO₃
2. Basic substances: KCl, MgO, CaO, Na₂CO₃
3. Neutral substances: NaCl, H₂O