# Test Paper for Atoms and Molecules

Given below are the Class 9 Science CBSE Test Paper for Atoms and Molecules
a. Concepts questions
b. Calculation problems
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## Concepts questions

Question 1
State the law of mass conservation.

Question 2
What do you understand by the law of constant proportion?

Question 3
Who was responsible for coining the term atom?

Question 4
What is an atom?

Question 5
What is a molecule?

Question 6
What is atomicity?

Question 7
Define atomic mass unit.

Question 8.
Define ion.

Question 9
Give two drawbacks of Dalton’s atomic theory?
Question 10

Question 11
(a)Explain how atoms exist.
(b)What do you understand by atomicity?
(c) Explain polyatomic ions.

Question 12
Explain atomic mass and gram atomic mass. Why does mass have different expressions viz, ‘u’ and ‘gm’?

Question 13
Define a mole. Give the importance of the mole.

Question 14.
H2O is the formula for water. What information do you get from this formula?

Question 15
Write down the formulae of:
(a)Sodium oxide
(b)Aluminium chloride
(c)Sodium Sulphide
(d)Magnesium hydroxide
(e)Magnesium nitride
(f)Calcium nitrate
(g)Sodium nitrite
(h) Aluminium sulphide
(i) Strontium fluoride
(j) Titanium (IV) oxide
(k) Calcium bromide

Question 16
Why are Dalton's symbol not used in chemistry?

Question 17
What is the difference between 2O, O2and O3.

## Calculation Problems

Question 18
How many molecules are present in 1 ml of water?

Question 19.
Calculate the molecular mass of glucose, C6H12O6.

Question 20
What is the formula unit mass of CaCl2and NaCl.
(Na = 23, Cl=35.5, Ca=40)

Question 21
10.0 g CaCO3 on heating gave 4.4 g of CO2 and 5.6 g of CaO. Show that these observations are in agreement with law of conservation of mass.

Question 22
Find out
(1) the mass of a single oxygen atom
(2) the mass of a single oxygen molecule
(3) the mass of a mole of oxygen gas
(4) the mass of an oxygen ion
(5) the number of atoms in a mole of an oxygen molecule.

Question 23
What is the atomicity of oxygen and phosphorous?

Question 24
How many moles of $SO_2$ have same mass as 3 moles of oxygen?

## Summary

This Class 9 Test Paper for Atoms and Molecules with answers is prepared keeping in mind the latest syllabus of CBSE . This has been designed in a way to improve the academic performance of the students. If you find mistakes , please do provide the feedback on the mail.