Sciencel class 9 exercise solution

7. What is the mass of—(a) 1 mole of nitrogen atoms? (b) 4 moles of aluminium atoms (Atomic mass of aluminium= 27)? (c) 10 moles of sodium sulphite (Na2SO3)?

6. Calculation of atomic masses of molecules (a) Ethyne, C2H2(b) Sulphur molecule, S8(c) Phosphorus molecule, P4 (Atomic mass of phosphorus= 31)(d) Hydrochloric acid, HCl(e) Nitric acid, HNO3.

4. Write the chemical formulae of the following. 5. Give the names of the elements present in the following compounds.

Question 3. What are polyatomic ions? Give examples.