Calculate the molar mass of the following substances.
$(a)$ Phosphorus molecule,$P_4$ (Atomic mass of phosphorus $= 31$)
$(b)$ Hydrochloric acid,$HCl$
$(c)$ Nitric acid,$HNO_3$

Why is it not possible to see an atom with naked eyes?

Calculate the molar mass of the following substances.
$(a)$ Ethyne,$(C_2H_2)$
$(b)$ Sulphur molecule,$(S_8)$

If one mole of carbon atoms weighs $12 \, g$,what is the mass (in grams) of $1$ atom of carbon?

In a reaction,$5.3 \, g$ of sodium carbonate reacted with $6 \, g$ of acetic acid. The products were $2.2 \, g$ of carbon dioxide,$0.9 \, g$ of water,and $8.2 \, g$ of sodium acetate. Show that these observations are in agreement with the law of conservation of mass.
$\text{Sodium carbonate} + \text{Acetic acid} \to \text{Sodium acetate} + \text{Carbon dioxide} + \text{Water}$

Hydrogen and oxygen combine in the ratio of $1:8$ by mass to form water. What mass of oxygen gas would be required to react completely with $3 \,g$ of hydrogen gas (in $,g$)?