What happens when aqueous solution of sulphuric acid comes in contact with blue litmus paper? 

Red

The correct answer is option 1. Red.

When an aqueous solution of sulfuric acid comes in contact with blue litmus paper, the litmus paper turns red. Sulfuric acid is a strong acid and it reacts with the blue litmus paper, causing it to change color to red. This is because the acid donates protons (H⁺ ions) to the litmus paper, making it acidic and causing the color change.