Which solvent from the following is used in order to avoid the creation of waste and the pollution of air?

Summarize the international standards for the concentration of various metals and ions in drinking water.

Which of the following is harmful to calcium-containing structures and is responsible for causing cough and throat irritation in humans?

Which gas is released when chlorine free radicals react with ozone?

Identify the reactions that occur in photochemical smog.
$(i)$ $CH_2=O + H_2 \longrightarrow CH_3OH$
$(ii)$ $NO_{2(g)} \xrightarrow{h \nu} NO_{(g)} + O_{(g)}$; $O_{(g)} + O_{2(g)} \longrightarrow O_{3(g)}$
$(iii)$ $CH_4 + 2O_3 \longrightarrow CH_2=O + 2H_2O$
$(iv)$ $NO_{(g)} + O_{3(g)} \longrightarrow NO_{2(g)} + O_{2(g)}$

What is the troposphere?