Which of the following equations illustrates the law of conservation of matter?

D.

Explanation:

As we know by the law of conservation of matter the total matter present initially and finally must be same in term of the amount or quantity.

So here we will check the amount of gases present before reaction and after reaction, if the amount remains same then in that case the matter will remain conserve always.

So here we will have the correct equation as

D.

here in above equation number of hydrogen atoms are same (i.e. 4) on both sides as well as amount of oxygen atoms are also same (i.e. 2) on both sides of the reaction

d. air pressure decreases as altitude increases.