The orchid seeds do not germinate under ordinary conditions because
A. Orchid seeds are too large for disposal
B. Orchid seeds do not have endosperm
C. Orchid seeds undergo a dormancy period
D. They germinate under very dry conditions
Answer: Option D
Ozone depletion is caused by the increase in the level of
A. Water vapour
B. Chlorofluro carbon (CFC)
C. Oxygen
D. Carbon monoxide
Which of the following is a beneficial activity of microorganisms?
A. Some microorganisms use carbon dioxide
B. Some microorganisms provide nitrogen for plant growth
C. Some microorganisms are used in sewage treatment
D. All the above
Which of the following parameters indicates the organic pollution of a water sample?
A. pH
B. Turbidity
C. Hardness
D. COD
The chemical system for removal of the ions of level of salt is called
A. Ion transfer
B. Ionization
C. Ion exchange
D. Ion vaporization
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