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:
- Acidic substances: HCl, H2SO4, HNO3
- Basic substances: KCl, MgO, CaO, Na2CO3
- Neutral substances: NaCl, H2O