21. The volume of 50 g of a substance is \( 20 cm^3 \). If the density of water is \( 1 g/cm^3 \) , will the substance float or sink?

We know that, \( Density \ = \ \frac{Mass}{Volume} \)

=> \( Density \ = \ \frac{50}{20} \ = \ 2.5 g/cm^3 \)

Density of water = \( 1 g/cm^3 \)

Density of the substance is greater than density of water. So the substance will float.