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:
1. | 37.33 | 2. | 45.85 |
3. | 25.75 | 4. | 43.13 |
The Prussian blue colour obtained during the test of nitrogen by Lassaigne's test is due to the formation of-
1. | Fe4[Fe(CN)6]3 | 2. | Na3[Fe(CN)6] |
3. | Fe(CN)3 | 4. | Na4[Fe(CN)5NOS] |
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 %