Question

Which of the following natural phenomenon’s releases chemicals which cause acid rains?
A. Volcanic eruptions
B. Lighting
C. Rotting vegetation
D. All

Answer 1

Hint: Acid rains are caused due to the emission of sulfur dioxide ($S{{O}_{2}}$) and oxides of nitrogen ($N{{O}_{X}}$ ) into the atmosphere and carried by the wind and air currents. The sulphur dioxide and oxides of nitrogen react with oxygen, water and other chemicals and form sulfuric acid and nitric acid. The formed acids mix with the rain water and come to the ground in the form of acid rain.

Complete answer:
- In the question it is given that which of the given options releases chemicals which cause acid rains.
- Coming to the options, option A, Volcanic eruptions. Volcano eruption is the natural cause which releases sulphur dioxide, hydrogen fluoride and carbon dioxide into the atmosphere in huge amounts.
- The formed sulphur dioxide reacts with oxygen and water droplets in the atmosphere and causes acid rain.
\[S{{O}_{2}}+{{O}_{2}}+{{H}_{2}}O\to {{H}_{2}}S{{O}_{4}}\]
- So, the option A is correct.
- Coming to option B, Lighting. At the time of lighting stroke the temperature rises to very high and at this high temperature the nitrogen and oxygen in the air reacts together and form nitric oxide (NO). The formed nitric oxide reacts with water and forms nitrous acid.
\[\begin{align}
  & {{N}_{2}}+{{O}_{2}}\xrightarrow{High\text{ }Temperature}2NO \\
 & 4NO+{{O}_{2}}+2{{H}_{2}}O\to \underset{Nitrous\text{ }acid}{\mathop{4HN{{O}_{2}}}}\, \\
\end{align}\]
- So, option B is also correct.
 - Coming to option C, Rotting vegetation. At the time of rotting, vegetables produce isoprene into the atmosphere. The released isoprene is going to oxidize in the troposphere and reacts with oxides of nitrogen and forms organic acids like acrylic acids. The formed acids acidify the rain water and cause rain water.
- So, the option C is also correct.
- Therefore all the given options cause acid rains.

So, option D is correct.

Note:
Everybody thinks that rotting vegetation does not affect the environment. But rotting vegetation indirectly causes the problems in the form of acid rains. The pH of the typical acid rain is 4.0. Acid rains cause a lot of problems to human beings, animals and trees.