A milkman adds a very small amount of baking soda to fresh milk.

(a) Why does he shift the pH of the fresh milk from 6 to slightly alkaline?

(b) Why does this milk take a long time to set as curd?

52 The acid produced naturally in our stomach is: 53 The daffodil plants grow best in a soil having a pH range of 6.0 to 6.5. If the soil in a garden has a pH of 4.5, which substance needs to be added to the soil in order to grow daffodils? 55 Which of the following elements would form oxides which would indicate pH values less than seven, using moist pH paper?

Magnesium, Carbon, Sulphur, Hydrogen, Copper.

56 The pH values of five solutions A, B, C, D and E are given below:

Which solution is (i) weakly alkaline (ii) neutral (iii) strongly acidic (iv) strongly alkaline, and (v) weakly acidic?