Sureshot questions from Study of compounds ICSE CHEMISTRY
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Give
one suitable reason for each of the followings
1.
Hydrogen
chloride gas dissolved using Funnel arrangement.
Reduces
back-suction and provides a large surface area for the absorption of HCl gas in
water.
2.
Quick
lime is not used as drying agent in the purification of Hydrogen chloride gas.
Hydrogen
chloride gas reacts with Calcium oxide and forms Calcium chloride and Water.
3.
Low
temperature is maintained in the laboratory preparation of Hydrogen chloride
gas.
Maintaining
high temperature causes fuel wastage and Sodium sulphate formed here forms a
hard crust inside the round bottom flask.
4.
Calcium
hydroxide is taken in excess amount in the preparation of Ammonia gas in
laboratory method.
Excess
Calcium hydroxide prevents the sublimation of Ammonium chloride.
5.
All
glass apparatus is used in the laboratory preparation of Nitric acid.
Nitric
acid vapours being highly corrosive destroys rubber or cork but does not affect
Glass.
6.
Nitric
acid prepared in laboratory method appears in yellow colour.
The
yellow tinge in Nitric acid is due to the dissolved Nitrogen dioxide in it.
7.
Dilute
Sulphuric acid can form two types of salts.
Sulphuric
acid is a dibasic acid.
State
one appropriate observation for each of the followings.
1.
Silver
nitrate solution is added to dilute hydrochloric acid then heated.
A
white precipitate is formed which dissolve on heating.
2.
Lead
nitrate solution is added to dilute Hydrochloric acid followed by excess
ammonium hydroxide.
A
white precipitate is formed which dissolves in Ammonium hydroxide.
3.
Barium
chloride solution is added to dilute Sulphuric acid.
A
white precipitate is formed
4.
Excess
Ammonia gas is passed into Copper sulphate solution.
A
pale blue precipitate turns into a deep blue solution.
5.
Conc.
Nitric acid is added to Copper turnings.
A
blue filtrate/ Reddish brown vapours evolved
6.
Dilute
Nitric acid is added to Copper turnings.
A
blue filtrate is formed
7.
Conc.
Sulphuric acid is added to Copper sulphate crystals.
Blue
crystals turns into white amorphous solid
8.
Conc.
sulphuric acid is added to sugar crystals.
A
black spongy mass is left.
9.
Dilute
Sulphuric acid is added to Copper oxide.
A
blue solution is formed.
10. A dilute acid is added to sodium
carbonate.
Brisk
effervescence of a colourless gas evolved which turns lime water milky but has
no effect on acidified Potassium permanganate.
11. A dilute acid is added to sodium sulphite.
A
suffocating colourless gas evolved which turns lime water milky decolourizes
acidified Potassium permanganate.
12. A dilute acid is added to Sodium
sulphide.
A
colourless gas with rotten egg smell evolved which turns Lead acetate paper to
silvery black.
