Which one is a decomposition reaction?

b no

Explanation:

because it is decomposing into two elements

As given below.

Explanation:

Yes, the scientist should be concerned about the acid rain precipitation and thus its a concern of the new environmentalists as acidic rain is caused by the compounds of sulfur and nitrogen and gases released in the air. This is due to the dangerous composition of gases that develops due to industrial clustering and regarded as highly hazardous for plant and animal life. The reproduction rate of birds and forest ecosystem is affected by the presence of the acid precipitation as this rain has a lower pH and can cause sens of burning and a feeling of irritation. Even the soils can be damaged by this rain, as microbes are unable to tolerate the hazardous acids and high concentration leads the ground vulnerable to erosion agents like wind and water.