Answer:
b.The volume increases.
Explanation:
We are given that a litre of water is heated from 20 degree celsius to 50 degree celsius .
Volume of water= 1litre
Volume of liquid is directly proportional to temperature
When volume of liquid increases then temperature is also increases .
When temperature is increases then the volume is also increases .
When temperature decreases then the volume of liquid decreases.
When temperature is increases from 20 degree celsius to 50 degree celsius then the volume of water increases.
Hence , option b is true,
Answer :b.The volume increases.