T1 CH6 Health and Hygiene — Science STD 7 — Question

Complete combustion of the fuel takes place and the colour of the flame is yellow and is the hottest part of the flame.

Fishes are aquatic vertebrates.

The image of right hand in a plane mirror looks like a left hand

Burning wood and coal causes pollution of air.

Plastics are environment friendly.

If the chemical properties of a substance remain unchanged and the appearance or shape of a substance changes it is called a periodic change.

Non-metals are non-malleable.

A substance which contains less number of molecules per unit volume is said to be denser.

A lot of plastic pollutes our environment.

Polyvinyl chloride has heavy metals such as cadmium and lead which are toxic and harmful to our health.