The percentage of oxygen present in air is approximately-
A). 44%
B). 23%
C). 40%
D). 21%
What are metal bearing rocks called?
A). Bitumen
B). Bauxite
C). Metalloids
D). Ores
Which is the absolute temperature scale?
A). Celsius
B). Fahrenheit
C). Kelvin
D). All of these
Which layer protects earth from harmful rays of the Sun?
A). Ionosphere
B). Ozone layer
C). Troposphere
D). Magnetosphere
Noise or Noise pollution measured in:
A). Phon
B). Deci
C). Decibel
D). Decimal