71.
Boron, Zinc and Manganese are usually referred to as

72.
_________ are used for converting saline or brackish water into pure distilled water.

73.
The primary cause of a radiation inversion is:

74.
Charged particles from the sun that travel through space at high speeds are called:

75.
All are particulate pollutants except

76.
The rate at which temperature decreases with increasing altitude is known as the:

77.
A set of organisms that resemble one another in appearance and behaviour is called a _____________

78.
Which of the following will decrease in a rising parcel of air?

79.
The pyramid of energy in terrestrial ecosystem is

80.
The pyramid of numbers in a single tree is