NCERT Class X Science Class: Chapter –5. Periodic Classification of Elements – Part-9

Download PDF of This Page (Size: 227K)

Question 44:

Atomic number of a few elements are given below

  1. Identify the elements

  2. Identify the Group number of these elements in the Periodic Table

  3. Identify the Periods of these elements in the Periodic Table

  4. What would be the electronic configuration for each of these elements?

  5. Determine the valency of these elements

Answer:

Elements- Neon (Ne)

Group- 18

Period- 2

Electron configuration- (2, 8)

Valency- 0

Elements- Calcium (Ca)

Group- 2

Period- 4

Electron configuration- (2, 8, 8, 2)

Valency- 2

Elements- Nitrogen (N)

Group- 15

Period- 2

Electron configuration- (2, 5)

Valency- 3

Elements- Silicon (Si)

Group- 14

Period- 3

Electron configuration- (2, 8, 4)

Valency-4

Question 45:

Complete the following cross word puzzle (Figure)

Across

(1) An element with atomic number 12.

(2) Metal used in making cans and member of group 14.

(3) A lustrous non-metal which has 7 electrons in its outermost shell.

Down

(2) Highly reactive and soft metal which imparts yellow colour when subjected to flame and is kept in kerosene.

(5) The first element of second period

(6) An element which is used in making fluorescent bulbs and is second member of group 18 in the modern periodic table.

(7) A radioactive element which is the last member of halogen family.

(8) Metal which is an important constituent of steel and forms rust when exposed to moist air.

(9) The first metalloid in modern periodic table whose fibres are used in making bullet-proof vests.

Image the cross word puzzle

Image the Cross Word Puzzle

Image the cross word puzzle

Answer:

Across

(1) An element with atomic number 12 is magnesium

(2) Metal used in making cans and member of group 14 is tin

(3) A lustrous non-metal which has 7 electrons in its outermost shell is iodine.

Down

(2) Highly reactive and soft metal which imparts yellow colour when subjected to flame and is kept in kerosene is sodium.

(5) The first element of second period is lithium.

(6) An element which is used in making fluorescent bulbs and is second member of group18 in the modern periodic table is neon.

(7) A radioactive element which is the last member of halogen family is astatine.

(8) Metal which is an important constituent of steel and forms rust when exposed to moist air is iron. (9) The first metalloid in modern periodic table whose fibres are used in making bullet-proof vests is boron.

Image the cross word puzzle with answer

Image the Cross Word Puzzle with Answer

Image the cross word puzzle with answer