General Science 8th Class Chapter 5 Periodic Table Solved Exercise

 General Science

8th Class

Chapter 5

Periodic Table

Questions

1. Encircle the correct option.

(i) An element of the third period in the Periodic Table:

a. H        b. P        c. He        d. Li

(ii) Mg belongs to the period of the Periodic Table:

a. 1st        b. 2nd        c. 3rd        d. 4th

(iii) An alkali metal:

a. F        b. Be        c. Al        d. Na

(iv) Ne belongs to:

a. nitrogen family        b. fluorine family        c. noble gases        d. alkaline earth metals

(v) An element of group 17 of the Periodic Table:

a. Cl        b. Ar        c. S        d. Si 

(vi) Atomic number of the element at fourth position in second period:

a. 4        b.5        c. 6        d. 7

(vii) How many periods are there in the Periodic Table?

a. Five        b. Six        c. Seven        d. Eight

(viii) A metal:

a. Cu        b. C        c. Cl        d. Ne

(ix) A non-metal:

a. H        b. Na        c. Li        d. Be

(x) An atom containing two electrons:

a. H        b. He        c. Li        d. Be

2 Write short answers.

(i) What is meant by a period in the Periodic Table?

Ans.

The horizontal rows of elements in the Periodic Table are called "Periods".

(ii) What is meant by a group of the Periodic Table?

Ans.

The vertical columns in the Periodic Table are called "Groups".

(iii) Define element.

Ans.

An element is a substance, which cannot split into two or more substances by ordinary chemical changes.

(iv) What do you mean by an atomic number?

Ans.

The number of protons present in an atom of an element is called atomic number (Z) of that element.

(v) How many electrons are there in the valence shell of H?

Ans.

There is one electron in the valence shell of H.