Mr Khanna had a pond in his garden, filled with all kinds of aquatic plants. He wanted to prevent mosquitoes from breeding in the pond without harming the plants in any way. He could __________.
(i) Add salt into the water
(ii) Add some goldfish into the pond
(iii) Spray a film of oil on the surface of the pond
A (i) only
B (ii) only
C (iii) only
D (i), (ii) and (iii)
B is correct. As goldfish eat the mosquitoe's eegs
Ans 5:
Class : Class 7
A: Because of the high salinity of the water, plants will die.B: Plants will have more CO2 and hence have a higher rate of photosynthesis.C: O2 and CO2 will stop dissolving in water, hence killing the plants.So best option is B.
Ans 9:
Class : Class 10
it should be not be c as oil can block the gas exchange for plants and can effect the plant