Why is it safer to use soap from the environmental point of view?

Mention the effects of acid rain.

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 .... .

In municipal sewage,$BOD$ values (in $ppm$) are

Which gas contributes the least to global warming?

How does the greenhouse effect contribute to global warming? Explain.