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Published on: 25/05/2021
QB365 Provides the updated NCERT Examplar Questions for Class 12 Biology, and also provide the detail solution for each and every ncert examplar questions , QB365 will give all kind of study materials will help to get more marks
Download CBSE Class 12th Standard CBSE Biology question papers, sample papers, important questions, and previous year solved papers in PDF format. Get free study materials, NCERT solutions, and exam preparation resources for Class 12th Standard CBSE Biology
Questions + Answers key
Take MCQ Biology Test1.
Algal blooms impart a distinct colour to water due to:
their pigments
excretion of coloured substances
formation of coloured chemicals in water facilitated by physiological degradation of algae.
absorption of light by algal cell wall.
2.
Nuisance growth of aquatic plants and bloom-forming algae in natural waters is generally due to high concentration of:
carbon
sulphur
calcium
phosphorus
3.
Catalytic converters are fitted into automobiles to reduce emission of harmful gases. Catalytic converters change unburnt hydrocarbons into:
carbon dioxide and water
carbon monoxide
methane
carbon dioxide and methene
4.
Photochemical smog is caused by a light mediated reaction between
NO2 and unsaturated hydrocarbons
NO2 and O3
SO2 and unburnt hydrocarbons
SO2 and O3
5.
A lake near a village suffered heavy mortality of fishes within a few days. Consider the following reasons for this.
(a) lots of urea and phosphate fertilizers were used in the crops in the vicinity
(b) the area was sprayed with DDT by an aircraft
(c) the lake water turned green and stinky
(d) phytoplankton populations in the lake declined initially thereby greatly reducing photosynthesis
Which two of the above were main reasons of fish mortality in the lake?
A, C
A, B
B, C
C, D
6.
Which one of the following is the correct percentage of the two green house gases that contribute to the total global warming?
N2O 6%, CO2 86%
methane 20%, N2O 18%
CFCs 14%, methane 20%
CO2 40%, CFCs 30%
7.
Ozone is spread in the swimming pool because
it acts as disinfectant
it absorbs UV radiations
ozone is easily available from O2
all of the above
8.
In a coal fired power plant electrostatic precipitators are installed to control emission of
NOX
SPM
CO
SO2
9.
Which one of the following statements pertaining to pollutants is correct?
DDT is a non-biodegradable pollutant
excess fluoride in drinking water causes osteoporosis.
excess cadmium in drinking water causes black foot disease.
methyl mercury in water may cause 'Itai Itai' disease.
10.
More than 70% of world's fresh water is contained in
polar ice
glaciers and mountains
Antarctica
Greenland
1.
(a)
their pigments
2.
(d)
phosphorus
3.
(a)
carbon dioxide and water
4.
(a)
NO2 and unsaturated hydrocarbons
5.
(b)
A, B
6.
(c)
CFCs 14%, methane 20%
7.
(a)
it acts as disinfectant
8.
(b)
SPM
9.
(a)
DDT is a non-biodegradable pollutant
10.
(a)
polar ice
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