IGCSE Chemistry: Specimen Questions with Answers 19 - 21 of 240

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Question 19

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Short Answer▾

Classify each of the following as either an element, compound or mixture.

Carbon dioxide (1 Marks)

Explanation

A compound made up of molecules containing one carbon atom and two oxygen atoms is an carbon dioxide. Carbon dioxide is normally found as a gas that is breathed out by animals and absorbed by green plants.

Question 20

Question

MCQ▾

Among the following, the atom of which element is bigger in size?

Choices

Choice (4)

a.

Potassium

b.

Lithium

c.

Hydrogen

d.

Sodium

Answer

a.

Explanation

Potassium and lithium both belong to group .

Group 1 of the modern periodic table is as follows:

Potassium and Lithium Both Belong to Group 1

As the number of shells increases down the group the size of the atom also increases. Since potassium is below all listed elements, hence an atom of potassium is bigger in size than that of rest.

Question 21

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Short Answer▾
  1. Iron from the blast furnace is impure. It contains 5 % of impurities, mainly carbon, sulfur, silicon and phosphorus. Almost all of this impure iron is converted into the alloy, mild steel.
    1. (i) State a use of mild steel.

[1 Marks]

Mild Steel is used for making pipe lines.

Images of Mild Steel Uses

Name and give a use of another iron-containing alloy.

name .

Explanation

Ferronickel is the alloy of iron and nickel

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