IGCSE Chemistry Paper-1: Specimen Questions with Answers 18 - 19 of 99

Question number: 18

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Question

Compound X is heated with carbon using the apparatus shown.

Brown solid is formed in the reaction tube and the limewater

Brown Solid is Formed in the Reaction Tube and the Limewater

A brown solid is seen in test tube and the limewater turns cloudy. What is X?

Choices

Choice (4)Response

a.

sodium oxide

b.

calcium oxide

c.

magnesium oxide

d.

copper (II) oxide

Answer

d.

Explanation

Compound X is Copper (II) oxide.

When Copper (II) oxide is heated with carbon following reaction take place:

2CuO + C - > 2Cu + Co2

When the CO2 reaches in the beaker following reaction takes place:

CO2 + Ca (OH) 2 - > CaCO3 + H2O

When carbon di oxide comes in contact with lime water it produces calcium carbonate and causes the white precipitation in the solution.

Question number: 19

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Question

Which alloy contains non-metal as its constituents?

Choices

Choice (4)Response

a.

Amalgam

b.

Brass

c.

Steel

d.

Bronze

Answer

c.

Explanation

Steels are alloys of iron and other elements, primarily carbon, widely used in construction and other applications. The carbon content of steel is between 0.002 % and 2.1 % by weight for plain iron-carbon alloys. These values vary depending on alloying elements such as manganese, chromium, nickel, iron, tungsten, carbon and so on. Basically, steel is an iron-carbon alloy.

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