21. The percentage content of carbon is found to be maximum in –
A. Anthracite
B. Bituminous
C. Peat
D. Lignite
22. The density of water is maximum at what temperature –
A. – 4 °C
B. + 4 °C
C. + 2.5 °C
D. 0 °C
23. Quartz is a compound of –
A. Calcium Sulphate
B. Calcium Silicate
C. Sodium Sulphate
D. Sodium Silicate
24. Who discovered inert gases?
A. Cavendish
B. Shelley
C. Ramse
D. Joseph Priestley
25. The gas used for filling up the tires of aircraft is –
A. Hydrogen
B. Helium
C. Nitrogen
D. Neon