CIE Chemistry (US-0439): Specimen Questions with Answers 200 - 202 of 240

Question number: 200

MCQ▾

Question

Which property of elements increases across a period of the Periodic Table?

Choices

Choice (4) Response

a.

Number of electron shells

b.

Number of outer shell electrons

c.

Metallic character

d.

Tendency to form positive ions

Answer

c.

Explanation

From right to left across a period, metallic character increases because the attraction between valence electron and the nucleus is weaker, enabling an easier loss of electrons. Metallic character increases as you move down a group because the atomic size is increasing

Question number: 201

MCQ▾

Question

Mass of 28 carbon atoms is equal to the mass of ________ hydrogen atoms.

Choices

Choice (4) Response

a.

333

b.

336

c.

334

d.

332

Answer

b.

Explanation

The atomic mass of carbon is while that of hydrogen is

Thus, mass of

Therefore, the mass of carbon atoms is equal to the mass of 336 hydrogen atoms.

Question number: 202

Short Answer Question▾

Write in Short

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.