NCERT Solutions for Chapter: Atoms and Molecules, Exercise 3: Long Answer Questions

The formula unit mass of ${\mathrm{Ca}}_3({\mathrm{PO}}_4{)}_2$ is _____.

(a) In this crossword puzzle, names of $11$ elements are hidden. Symbols of these are given below. Complete the puzzle.

 1. $\mathrm{Cl}$                  7. $\mathrm{He}$

 2. $\mathrm{H}$                   8. $\mathrm{F}$

 3. $\mathrm{Ar}$                  9. $\mathrm{Kr}$

 4. $\mathrm{O}$                 10. $\mathrm{Rn}$

 5. $\mathrm{Xe}$               11. $\mathrm{Ne}$

 6. $\mathrm{N}$

(b) Identify the total number of inert gases, their names and symbol from this crossword puzzle.

Write the formula for the following and calculate the molecular mass.

Caustic potash

Write the formula for the following and calculate the molecular.

Baking powder

Write the formula for the following compound and calculate its molecular mass.

Limestone

Write the formula for the following and calculate the molecular mass.

Caustic soda

Write the formula for the following and calculate the molecular mass.

Ethanol

Write the formula for the following and calculate the molecular mass.

Common salt