WBCS Mains 2018 Official Paper-VI

Assertion (A): Graphite is slippery and is used as a lubricant.
Reason (R): Graphite has free electrons.

Assertion (A): The use of chlorofluorocarbons is banned throughout the world nowadays.
Reason (R): These chemicals cause skin cancer.

Assertion (A): Indus Valley people knew the art of navigation.
Reason (R): Indus Valley seals indicate prevalence of overseas trade.

Assertion (A): The pouring of kerosene oil on stagnant pools helps to eradicate malaria.
Reason (R): The kerosene oil is poisonous for the mosquitoes.

Assertion (A): When lightning strikes, the sound is heard a little after the flash is seen.
Reason (R): The velocity of light is greater than that of sound.