1. The most important water quality parameter for domestic use of water is ______.
[A] non-carbonate hardness
[B] carbonate hardness
[C] chlorides
[D] coliform group of organisms
Answer: Option D
2. Water table drops by 3 m in irrigable land of 50 hectare. If porosity and specific retention are 0.30 and 0.10 respectively, the change in storage in hectare-meter is _____.
[A] 60
[B] 15
[C] 30
[D] 45
Answer: Option C
Explanation:
specific yield + specific retention = porosity
Sy = 0.30 – 0.10 = 0.20
Change in storage = 50 × 3 × 0.2 = 30 Ha-m
3. The minimum dissolved oxygen content (ppm) in a river necessary for the survival of aquatic life is _____.
[A] 2
[B] 4
[C] 0
[D] 8
Answer: Option C
4. Particulate matter (fly ash) carried in effluent gases from the furnaces burning fossil fuels are better removed by _____.
[A] Cyclone
[B] Cotton bag house filter
[C] Wet scrubber
[D] Electrostatic precipitator (ESP)
Answer: Option D
5. Population levels over 5 decades of a small town are given below. Population for the years 1960, 1970, 1980, 1990 and 2000 is 2,50,000, 2,80,000, 3,40,000, 4,20,000 and 4,90,000 respectively. The population of the town in the year 2020 estimated by Arithmetic Increase method will be _____.
[A] 6,90,000
[B] 6,10,000
[C] 5,90,000
[D] 3,10,000
Answer: Option B
Explanation:
Average increase per decade = (30000 + 60000 + 80000 + 70000)/4
= 60000 P_{2020} = P_{2000} + 2 * 6000
= 4,90,000+1,20,000 = 6,10,000