CIE Chemistry (US-0439): Specimen Questions with Answers 31 - 32 of 240

Question number: 31

Short Answer Question▾

Write in Short

Aluminum and gallium are in Group III of the Periodic Table.

  1. The heat from your hand is sufficient to melt gallium.

    Describe the change in state from solid to liquid in terms of the kinetic particle theory. In your answer include

    • the difference in arrangement and closeness of the particles in a solid and a liquid,

    • the difference in the motion of the particles in a solid and a liquid.

      …………………………………………………………………………………………………………………

      …………………………………………………………………………………………………………………

      …………………………………………………………………………………………………………………

      …………………………………………………………………………………………………………………

      ………………………………………………………………………………………………….

Explanation

Elemental gallium is a soft, silvery blue metal at standard temperature and pressure, a brittle solid at low temperatures, and a liquid at temperatures greater than (above room temperature, but below the normal human body temperature). The melting point of gallium is used as a temperature reference point. So the gallium become liquid when comes in contact of human body. The kinetic human theory is given by diagram.

The kinetic human theory

The Kinetic Human Theory

The kinetic human theory

Question number: 32

MCQ▾

Question

The number of valence electrons in the group is ________.

Choices

Choice (4) Response

a.

3

b.

2

c.

4

d.

1

Answer

b.

Explanation

Valence electrons are the electrons present in the outermost shell of an atom. The number of valence electrons is equal to the group number. Therefore the number of valence electrons of the elements in .

It can be observed from the following table that each element in 2nd group have 2 valence electrons.

element in 2<sup/>nd</sup> group have 2 valence

element in 2nd group have 2 valence

element in 2nd group have 2 valence electrons. Group 2 Electronic Configuration Number of valence electron