Mass of body = 70 kg

Volume of water displaced = 20,000 cm^{3} = 0.02 m^{3}

(i) Mass of body immersed in water = mass of the water displaced

= volume of water displaced × density of water

= 0.02 × 1000

= 20 kg

Weight of the body = mg = 70 × g = 70 kgf

Weight of water displaced = mg = 20 × g = 20 kgf

Weight of body in water = weight of body in air – upthrust due to liquid

= 70 kgf – 20 kgf [∵ upthrust is equal to the weight of water displaced]

= 50 kgf

(ii) Density = Mass\over Volume

= 70\over 0.02 = 3500 kg m^{-3}

RD of body = 3500\over 1000 = 3.5

Therefore,

**Relative density of body = 3.5**