IGCSE Chemistry: Specimen Questions with Answers 202 - 203 of 240

Question number: 202

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Short Answer Question▾

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In the presence of sulfuric acid, hydrogen peroxide reacts with iodide ions to form iodine and water. This involves the reduction of hydrogen peroxide.

What is the meaning of the term reduction?

………………………………………………………………………………………………

Explanation

Reduction is a chemical reaction that involves the gaining of electrons by one of the atoms involved in the reaction. The term refers to the element that accepts electrons, as the oxidation state of the element that gains electrons is lowered.

An example of a reduction is when iron reacts with oxygen, forming a chemical called rust. In that example, the iron is oxidized and the oxygen is reduced.

Question number: 203

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Question

Saturated hydrocarbons are those which have ________ bond (s) only between all the adjacent carbon atoms of the organic compound.

Choices

Choice (4) Response

a.

Triple

b.

Single

c.

Double

d.

Question does not provide sufficient data or is vague

Answer

b.

Explanation

  • Saturated hydrocarbons are those which have single bond (s) only between all the adjacent carbon atoms of the organic compound. Alkanes are saturated hydrocarbons.

  • For example, propane , an alkane, is a saturated hydrocarbon.

Image shows the structure of propane

Image Shows the Structure of Propane

Image shows the structure of propane

  • Similarly all other alkanes have single bonds between each and every adjacent carbon atoms. Thus they are saturated hydrocarbons.