The relative contribution of $O_3$,$N_2O$,and $H_2O$ to global warming is in the ratio of ......

The measured $BOD$ values for four different water samples $(A - D)$ are as follows:
$A = 3 \, ppm; B = 18 \, ppm; C = 21 \, ppm; D = 4 \, ppm.$
The water samples which can be called as highly polluted with organic wastes,are .... .

Which of the following diseases increases in prevalence due to the greenhouse effect?

Determine whether the following statements are true or false:
$(1)$ The lowest region of the atmosphere where all living organisms,including humans,reside is called the troposphere.
$(2)$ The troposphere extends up to a distance of $25 \ km$ from sea level.
$(3)$ The region between $10 \ km$ and $50 \ km$ from sea level is called the stratosphere.
$(4)$ The ozone layer that protects living organisms is located in the troposphere.

Which of the following gases causes depletion in the ozone layer?

State whether the following statements are true or false:
$(1)$ The concentration of oxygen in cold water is $100 \ ppm$.
$(2)$ If the concentration of dissolved oxygen in water is less than $6 \ ppm$,the growth of fish gets inhibited.