Question : Which of the following statements is correct?

Option 1: Living organisms can survive a wide range of pH changes.

Option 2: When the pH of rainwater is less than 8.2, it is called acid rain.

Option 3: Our body works within the pH range of 7.0 to 7.8.

Option 4: Tooth decay starts when the pH of the mouth is lower than 1.5.

Question : Ramesh marks his article at Rs. 6,000, and after allowing a discount of 20%, he still earns a 60% profit. What is the cost (in Rs.) of the article?

Option 1: 3,600

Option 2: 4,800

Option 3: 3,000

Option 4: 4,200

Question : The pH of lemon juice is expected to be

Option 1: equal to 7

Option 2: nothing can be predicted

Option 3: less than 7

Option 4: more than 7