Question

Given below are the steps to test the presence of proteins in a food item.

1. Take a small quantity of the food item in a test tube, add 10 drops of water to it and shake it.
2. Make a paste or powder of food to be tested.
3. Add 10 drops of caustic soda solution to the test tube and shake well.
4. Add 2 drops of copper sulphate solution to it.

Which of the following is the correct sequence of the steps?

Options

• i, ii, iv, iii

• ii, i, iv, iii

• ii, i, iii, iv

• iv, ii, i, iii

Answer 1

ii, i, iv, iii

Explanation - 

To test the presence of proteins in a food item, first make a paste or powder of food to be tested (ii), then take small quantity of the food item in a test tube, add 10 drops of water to it and shake it (i). After that add 2 drops of copper sulphate solution to it (iv), and finally add 10 drops of caustic soda solution to the test tube and shake well (iii). Let the test tube stand for a few minutes and observe the colour of the solution in the test tube. Appearance of violet colour indicates the presence of proteins in the given food item.