Question

oxides of sulphur and nitrogen combine with rain water to form what and what which cause what

Answer 1

Oxides of Sulphur and Nitrogen combine with rain water to form Acid rain.

And acid rain causes many harmful effects to earth, like poisoning of crops, and death  of small insects etc.

Answer 2

Acid rain is caused by a chemical reaction that begins when compounds like sulfur dioxide and nitrogen oxides are released into the air. These substances can rise very high into the atmosphere, where they mix and react with water, oxygen, and other chemicals to form more acidic pollutants, known as acid rain.