Nitric acid is added to sodium extract before adding silver nitrate for testing halogens because:

1. Nitric acid reduces sulphide

2. Nitric acid decomposes NaCN and Na₂S

3. Nitric acid oxidises the organic compound

4. Nitric acid acts as a dehydrating agent

In Kjeldahl’s method for estimation of nitrogen present in the soil sample, ammonia evolved from 0.75g of sample neutralized 10ml. of 1M H₂SO₄. The percentage of nitrogen in the soil is:

The Prussian blue colour obtained during the test of nitrogen by Lassaigne's test is due to the formation of-

0.2 g of an organic compound on complete combustion produces 0.44 g of CO₂. The percentage of carbon is -

1. 50%

2. 60%

3. 70%

4. 80%

In sulphur estimation, 0.157 g of an organic compound gave 0.4813 g of barium sulphate. The percentage of sulphur in the compound is-

1. 39.10 %

2. 48.13 %

3. 42.10 %

4. 52. 43 %