Chapter : 2 Important Questions For Revision

Class 10

Chapter : 2

Acids, Bases And Salts

Important Questions

1. Classify compound on the basis of chemical properties.

Ans:- On the basis of chemical properties, all the compounds can be classified into three groups -

• Acids
• Bases
• Salts (neutral)

2. What is indicator ? Give examples of natural and artificial indicators. 

And:- Indicator - An indicator is a 'dye' that changes colour when it is put into an acid or a base.

Example :- 

Natural indicator - Litmus and turmeric

Artificial indicator - Methyl orange and phenolphthalein.

3. Define Acid. Give example.

And:- Acid - Acids are those chemical substances which have a sour taste.

Example:- 

Organic acid - Acetic acid, Citric acid, Lactic acid, Tartaric acid , oxalic acid & formic acid.

Mineral acid - HCl (Hydrochloric acid), H2SO4 (Sulphuric acid) & HNO3 (Nitric acid)

Some Organic Acids And Their Sources

• Acetic acid  - Vinegar
• Citric acid  - Lemon and Orange
• Lactic acid - Curd and Milk
• Tartaric acid - Unripe grapes and Tamarind
• Oxalic acid - Tomato
• Formic acid - Ant sting 

4.Give chemical properties of Acids.

Ans:-

• Acid reacts with Metals to form Hydrogen gas.

Zn  +  H2SO4  -  ZnSO4 + H2 ^

Zinc   sulphuric acid    zinc sulphate  hydrogen gas

Hydrogen gas burns with making a 'pop' sound.

• Acid react with Metal Carbonate to form CO2 gas.

Na2CO3 + 2HCl - 2NaCl + H2O + CO2 

Sodium Carbonate     -- Carbon dioxide

• Acid reacts with Bases to form salt and water.

NaOH  +  HCl  -- NaCl  + H2O

Sodium Hydroxide     Sodium chloride (salt)

The reaction between an acid and a base to form salt and water is called neutralisation reaction.

• Acid reacts with Metal oxide to form salt and water.

CuO  +  2HCl  --  CuCl2 + H2O

Copper oxide (black colour)   Copper chloride (blue-green colour)

• Acids have corrosive nature.
• The mineral acid cause severe burns on the skin & attack and eat up material like cloth, wood, metal structure and stone work . So , they are said to be corrosive.

Acids never stored in metal container because they gradually corrode and eat up the metal container.

5. What do all acids have in common ?

Ans:- A common thing in all the acid is that they produce hydrogen ion (H+) when dissolve in water.

HCl -- H+  +  Cl-

H2SO4  -- 2H+  +  SO4 --

6. What are the strong acids and weak acids ?

Ans:- An acid which is completely ionised in water and produce a large number of hydrogen ion is called strong acid.

e.g.  HCl, H2SO4 and HNO3

  HCl --  H+  + Cl-

         An acid which is partially ionised in water and produce a small number of hydrogen ion is called weak acid.

e.g.  Carbonic acid (H2CO3), Sulphurus acid (H2SO3), Acetic acid (CH3COOH), etc.

    CH3COOH   --  CH3COO-   +  H+

Acetic acid          Acetate ion