CLASS VII - SCIENCE - WORKSHEET- 4 - ATOMIC STRUCTURE- ANSWERS

 WORKSHEET - 4

ATOMIC STRUCTURE

I. Multiple choice questions.

1. What is the average diameter of an atom?

Ans: a. 1 X 10-9m


2. _______ and ______ are particles called as nucleons.

Ans: c. Proton, Neutron


3. In a neutral atom, the number of protons are equal to ________.

Ans: b. Number of electrons


4. A chlorine atom has ____ protons _____ electrons and _____ neutrons.

Ans: 17,17,18


5. Sodium ion( Na+) has _____ number of electrons.

Ans: a. 10


6. Which of the following has equal number of neutrons and protons?

Ans: b. Deuterium and d. Calcium


7. A sulphur atom contains 16 protons and 16 neutrons. Calculate its atomic number and mass number.

Ans: a. 16,32


8. In 5B11 atom, find the number of protons, neutrons and electrons?

Ans: 5,6,5

9. X and Y are two atomic species.



X

Y

No of Proton

9

9

No of Neutron

9

10


Select the correct statement about X and Y

Ans: c. X and Y have different physical properties


10. Pick out the isobar pair.

Ans: 18Ar40, 20Ca40


11. Atomic number and mass number of sodium atom are 11 and 23 respectively. Find the number of neutrons in this atom?

Ans: c.12


12. Mg → Mg2+ + ____

Ans: a. 2 Electrons


13. Methane comprises of ______.

Ans: 1 carbon, 4 hydrogen


II. Answer briefly.

14. Draw the basic structure of an atom representing its

a)Electrons, b) Nucleus

1`5. Who am I?

  1. I am essential to human beings for their healthy teeth and bones.

Ans: Calcium

  1. I am 78% in the air. I am responsible for growth of plants.

Ans: Nitrogen

  1. I am used to kill bacteria in drinking water.

Ans: Chlorine


16. Find the values of A,B,C,D in the table.


Element

Atomic number

Mass number

No of protons/

No of electrons

No of neutrons

Calcium

20

40

20

20

Chlorine

17

35

17

18

Nitrogen

7

14

7

7

Phosphorous

15

31

15

16

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