Class 10 Science Acids, Bases and Salts questions with solutions

Q 21 :
Which of the following salts do not contain water of crystallisation?

Blue vitriol
Baking soda
Washing soda
Gypsum

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(2)

Baking soda is sodium bicarbonate $(N a H C O_{3})$ in anhydrous form without any water of crystallisation.
Other options:
Blue Vitriol: It is hydrated salt of copper sulphate containing 5 molecules of water of crystallisation $(C u S O_{4} \cdot 5 H_{2} O)$ .
Washing soda: It is hydrated salt of sodium carbonate containing 10 molecules of water of crystallisation $(N a_{2} C O_{3} \cdot 10 H_{2} O) .$
Gypsum: It is hydrated salt of calcium sulphate containing 2 molecules of water of crystallisation $(C a S O_{4} \cdot 2 H_{2} O)$ .

Q 22 :
The chemical formula for plaster of Paris is:

$C a S O_{4} \cdot 2 H_{2} O$
$C a S O_{4} \cdot H_{2} O$
$C a S O_{4} \cdot 1 / 2 H_{2} O$
$2 C a S O_{4} \cdot H_{2} O$

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(3)

The chemical formula of plaster of Paris is $C a S O_{4} \cdot 1 / 2 H_{2} O$ . The half a molecule of water in the formula means that two molecules of $C a S O_{4}$ share one molecule of water so that the effective water of crystallisation for one $C a S O_{4}$ unit comes to half a molecule of water.

Q 23 :
Baking soda is a mixture of:

Sodium carbonate and acetic acid
Sodium carbonate and tartaric acid
Sodium hydrogen carbonate and tartaric acid
Sodium hydrogen carbonate and acetic acid

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(3)

Baking soda is a mixture of sodium hydrogen carbonate $(N a H C O_{3})$ and mild edible tartaric acid.

Q 24 :
Sodium hydrogen carbonate when added to acetic acid evolves a gas. Which of the following statements are true about the gas evolved?

(i) It turns lime water milky.
(ii) It extinguishes a burning splinter.
(iii) It dissolves in a solution of sodium hydroxide.
(iv) It has a pungent odour.

(i) and (ii)
(i), (ii) and (iii)
(ii), (iii) and (iv)
(i) and (iv)

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(2)

The gas evolved is carbon dioxide gas and it has the property to extinguish a burning splinter. It can turn lime water milky and gets dissolved in a solution of sodium hydroxide to form sodium carbonate. It is an odourless gas, hence the statement (iv) is false.

Q 25 :
Match the chemical substances given in Column (A) with their appropriate application given in Column (B):

Column ‘A’ Column ‘B’

(A) Bleaching Powder (i) Preparation of glass

(B) Baking soda (ii) Production of H? and Cl?

(C) Washing soda (iii) Decolourisation

(D) Sodium chloride (iv) Antacid

Column ‘A’	Column ‘B’
(A) Bleaching Powder	(i) Preparation of glass
(B) Baking soda	(ii) Production of H? and Cl?
(C) Washing soda	(iii) Decolourisation
(D) Sodium chloride	(iv) Antacid

A–(ii) B–(i) C–(iv) D–(iii)
A–(iii) B–(ii) C–(iv) D–(i)
A–(iii) B–(iv) C–(i) D–(ii)
A–(ii) B–(iv) C–(i) D–(iii)

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(3)

Bleaching powder $(C a O C l_{2})$ :
It is used for bleaching or decolourisation of clothes. Bleaching powder on reaction with water decomposes and releases chlorine, which acts as an oxidising, bleaching and disinfecting agent.
Baking soda $(N a H C O_{3})$ :
It is used as an antacid for relieving stomach acidity. They react with excess acid in the stomach and neutralises it.
Washing soda $(N a_{2} C O_{3})$ :
It is used in preparation of glass, soap and paper industries.
Sodium chloride (NaCl):
Aqueous sodium chloride is used for the production of $H_{2}$ and $C l_{2}$ gases on electrolysis.

Q 26 :
Which of the following oxide(s) of iron would be obtained on prolonged reaction of iron with steam?

FeO
$F e_{2} O_{3}$
$F e_{3} O_{4}$
$F e_{2} O_{3} a n d F e_{3} O_{4}$

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(3)

On prolonged heating with steam, iron produces a mixed oxide of $F e_{3} O_{4}$ with the evolution of hydrogen gas.

$3 F e + 4 H_{2} O ⟶ F e_{3} O_{4} + 4 H_{2}$

Topic Question Set

Q 21 :
Which of the following salts do not contain water of crystallisation?

Q 22 :
The chemical formula for plaster of Paris is:

Q 23 :
Baking soda is a mixture of:

Q 24 :
Sodium hydrogen carbonate when added to acetic acid evolves a gas. Which of the following statements are true about the gas evolved?

(i) It turns lime water milky.
(ii) It extinguishes a burning splinter.
(iii) It dissolves in a solution of sodium hydroxide.
(iv) It has a pungent odour.

Q 26 :
Which of the following oxide(s) of iron would be obtained on prolonged reaction of iron with steam?

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Topic Question Set

Q 21 : Which of the following salts do not contain water of crystallisation?

Q 22 : The chemical formula for plaster of Paris is:

Q 23 : Baking soda is a mixture of:

Q 24 : Sodium hydrogen carbonate when added to acetic acid evolves a gas. Which of the following statements are true about the gas evolved? (i) It turns lime water milky. (ii) It extinguishes a burning splinter. (iii) It dissolves in a solution of sodium hydroxide. (iv) It has a pungent odour.

Q 26 : Which of the following oxide(s) of iron would be obtained on prolonged reaction of iron with steam?

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Q 21 :
Which of the following salts do not contain water of crystallisation?

Q 22 :
The chemical formula for plaster of Paris is:

Q 23 :
Baking soda is a mixture of:

Q 24 :
Sodium hydrogen carbonate when added to acetic acid evolves a gas. Which of the following statements are true about the gas evolved?

(i) It turns lime water milky.
(ii) It extinguishes a burning splinter.
(iii) It dissolves in a solution of sodium hydroxide.
(iv) It has a pungent odour.

Q 26 :
Which of the following oxide(s) of iron would be obtained on prolonged reaction of iron with steam?