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Chemistry [2 Mark Question Answer]

Practical Work · ICSE STD 10 (ICSE - English Medium). 9 questions.

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[2 Mark Question Answer]

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9 questions · timed · auto-graded

Question 12 Marks
Distinguish by a chemical test,
Sulphuric acid from nitric acid and hydrochloric acid.
Answer
Add barium chloride solution to sulphuric acid, nitric acid, and hydrochloric acid. A white precipitate is formed in dilute sulphuric acid, and no such precipitate is formed in nitric acid and hydrochloric acid.
$
BaCl _{2( aq )}+ H _2 SO _{4( aq )} \longrightarrow BaSO _{4( s )}+2 HCl _{( aq )}
$
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Question 22 Marks
Distinguish by a chemical test,
Ammonium sulphate and sodium sulphate
Answer
Ammonium sulphate and sodium sulphate:

These salts can be distinguished by using KOH. When KOH is added to ammonium sulphate, ammonia gas is evolved. Whereas there is no evolution of ammonia gas in case of sodium sulphate.

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Question 32 Marks
Distinguish by a chemical test,
Sodium hydroxide solution and ammonium hydroxide solution.
Answer
Sodium hydroxide solution and ammonium hydroxide solution:

These salts can be distinguished by using metal cation like calcium. When we add calcium salt to sodium hydroxide and ammonium hydroxide, then a white curdy ppt. is formed only in the case of sodium hydroxide.

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Question 42 Marks
Distinguish by a chemical test,
Sodium chloride and sodium sulphite
Answer
Sodium thiosulphate and sodium sulphite:The salts can be distinguished by using silver acetate. To the salt silver acetate and dil. $\mathrm{HNO}_3$ are added. If there is formation of a white precipitate which slowly turns black then it is thiosulphate anion since silver acetate forms $\mathrm{Ag}_2 \mathrm{~S}_2 \mathrm{O}_3$ which being unstable in acid solution gets converted to black $\mathrm{Ag}_2 \mathrm{~S}$.
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Question 52 Marks
Distinguish by a chemical test,
Sodium carbonate and sodium sulphite
Answer
Sodium carbonate and sodium sulphite can be distinguished by using acidified $K_2Cr_2O_7$:
Take a small quantity of salt in a test tube; add dil. $H_2SO_4$.and warm if necessary. Now if on bringing a filter paper moistened with acidified $K_2Cr_2O_7$​​​​​​​ near the gas evolved, the orange colour of the paper turns green then it is sodium sulphite.
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Question 62 Marks
Copy and complete the following table which refers to the action of heat on some carbonates:

Carbonate Colour of residue on cooling
Zinc Carbonate

Lead Carbonate

Copper Carbonate
Answer
Carbonate Colour of residue on cooling
Zinc Carbonate white
Lead Carbonate yellow
Copper Carbonate black
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Question 72 Marks
When an ammonium salt is warmed with a sodium hydroxide solution, ammonia gas is evolved. State three ways in which you could identify this gas.
Answer
The three ways are:
  1. Ammonia gas turns moist red litmus blue.
  2. If a rod dipped in concentrated $HCl$ is brought near the gas, dense white fumes of $NH_4Cl$ are formed.
  3. The gas turns colourless Nessler's reagent i.e. $K_2HgI_4$ brown.
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Question 82 Marks
The questions (i) to (v) refer to the following salt solutions listed A to F.
A.Copper Nitrate
B.Iron (II) Sulphate
C.Iron (III) chloride
D.Lead Nitrate
E.Magnesium sulphate
F.Zinc chloride
(I)Which two solutions will give a white precipitate when treated with dilute hydrochloric acid followed by a barium chloride solution?
(II)Which two solutions will give a white precipitate when treated with dilute nitric acid followed by silver nitrate solution?
(III)Which solution will give white precipitate, when either dilute hydrochloric acid or dilute sulphuric acid is added to it?
(IV)Which solution becomes a deep/inky blue colour when the excess of ammonium hydroxide is added to it?
(V)Which solution gives a white precipitate with an excess of ammonium hydroxide solution?
Answer
(I)Iron (II) Sulphate and Magnesium sulphate
(II)Iron (III) chloride and Zinc Chloride
(III)Lead nitrate
(IV)Copper nitrate.
(V)Lead nitrate.
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Question 92 Marks
State your observation when:
Decomposition of bicarbonates by dil. $H _2 SO _4$
$2 NaHCO_3+H_2 SO_4 \rightarrow Na_2 SO_4+2 H_2 O+2 CO_2$
$2 KHCO_3+H_2 SO_4 \rightarrow K_2 SO_4+2 H_2 O+2 CO_2$
Answer
Dilute sulphuric acid liberates carbon dioxide from metallic carbonates and bicarbonates. Carbon dioxide, when bubbled into a test tube containing calcium hydroxide solution, turns it milky.
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[2 Mark Question Answer] - Chemistry STD 10 Questions - Vidyadip