Class 9 final Questions paper of only Chemistry of ch 3 and 4

NAVY CHILDREN SCHOOL
CLASS 9
CHEMISTRY
CH-3 AND 4

Given on : 17 feb 2026 Total Marks : 15

Q1. Define atomicity. ​ ​ ​ ​ ​ ​ ​ ​ (1)

Q2. Write the atomicity of the following molecules: ​ ​ ​ ​ (1)
(i) Sulphur (ii) Phosphorus

Q3. Give one word for the following: ​ ​ ​ ​ ​ ​ (1)
(i) A group of atoms carrying a charge (ii) Positively charged ion

Q4. Which of the following symbols of elements are incorrect? Give their correct
symbols. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (2)
(a) Cobalt CO (b) Carbon c (c) Aluminium AL (d) Sodium So

Q5. Calculate the formula mass of sodium carbonate (Na2CO3.10H2O). ​ ​ (2)

Q6. Calculate the mass per cent of Carbonate present in the molecule of calcium
carbonate. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (2)

Q7. Find the ratio of mass of the combining elements in the following compounds:
(a) CaCO3 (b) MgCl2 ​ ​ ​ ​ ​ ​ (1)

Q8. What is the maximum number of electrons which can be accommodated in K,L,M
and N shell? ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (2)

Q9. Why do helium, neon and argon have a zero valency? ​ ​ ​ ​ (1)

Q10. An element ‘X’ has a valency 3(+): ​ ​ ​ ​ ​ (2)
(a) Write the formula of its phosphide. (b) Write the formula of its carbonate.