Acids, Bases and Salts – Maharashtra Board Class 7 Solutions for General Science (English Medium)
|1.||Acids are sour in taste.||
Bases have a sharp astringent taste.
|Acids turn blue litmus paper red.||Bases turn red litmus paper blue.|
|3.||They are not soapy to touch.||
They are soapy to touch.
|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
An indicator reacts with an acid or a base. Salt is a neutral substance, so an indicator will not react with it.
Salt and water are formed as a result of a neutralisation reaction.
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.
- 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.
|3. Tartaric acid|
4. Lactic acid
|2. Citric acid|
|(d) Acetic acid||
- False. Common salt is neutral.
- False. Salts are formed by the neutralisation reaction between acids and bases.
- 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.
- Acidic substances: HCl, H2SO4, HNO3
- Basic substances: KCl, MgO, CaO, Na2CO3
- Neutral substances: NaCl, H2O