Question

how the pH value of the solution is changed when co2 gas is paced through pure water
1- remains constant
2-increases
3-Decreases
4-remain constant for some time and then increases

Answer 1

heya man !

When CO2 ( carbon dioxide ) is passed through H2O ( water ) , then it reacts with water to form H2CO3 ( Carbonic acid ) . 

We know that , 

acid reduces the value of pH .

So , 

pH will be less than 7 in this case . 

thnks :--- himanshu jha ✌✌