For purifying drinking water, Alum(Phitkari) is used?
A. To kill bacteria
B. To remove salt
C. For solidification of mud
D. To Remove Gases
The ozone layer restricts?
A. Ultraviolet radiation.
Chemical name of laughing gas is?
A. Nitrous oxide.
The hardest substance available on Earth is?
A. Diamond.
Which gas is filled in light electric bulb?
A. Nitrogen.