IGCSE Chemistry: Specimen Questions with Answers 9 - 12 of 240

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Question 9

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All metal nitrates decompose when heated. A few form a nitrite and oxygen. Most form the metal oxide, oxygen and a brown gas called nitrogen dioxide.

Almost all samples of nitrogen dioxide are an equilibrium mixture of nitrogen dioxide, NO2, and dinitrogen tetroxide, .

Explanation

In the forward reaction, a bond forms between the two nitrogen dioxide molecules.

Question 10

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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.

use [2 Marks]

Explanation

It is used in the production of non-ferrous alloys (12 %) , alloy steels (5 %) , plating (7 %) , foundry (3 %) and batteries (2 %) .

Question 11

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Answer the following questions about these structures. Each structure can be used once, more than once or not at all.

Structures of Five Atoms

Which two structures are hydrogen atoms? … and …

Explanation

Correct option is A and E because hydrogen have one electron in its outer most shell or valence shell.

Question 12

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Ethanoic acid can be used as a solvent. What is the meaning of the term solvent? … (1)

Explanation

A solvent is a substance that dissolves a solute, resulting in a solution. A solvent is usually a liquid but can also be a solid, a gas, or a super critical fluid. Here solvent is Ethanoic acid.

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