Principles Related to Practical Chemistry

Molar mass of the salt from NaBr, NaNO3, KI and CaF2 which does not evolve coloured vapours on heating with concentrated H2SO4 is g mol-1. (Molar mass in g mol-1 : Na : 23, N : 14, K : 39, O : 16, Br : 80, I : 127, F : 19, Ca : 40)

The fragrance of flowers is due to the presence of some steam volatile organic compounds called essential oils. These are generally insoluble in water at room temperature but are miscible with water vapour in vapour phase. A suitable method for the extraction of these oils from the flowers is -

1. distillation
2. steam distillation
3. distillation under reduced pressure
4. crystallisation

Given below are two statements : In the light of the above statements, choose the most appropriate answer from the options given below :

1. Both Statement I and Statement II are false
2. Statement I is true but Statement II is false
3. Both Statement I and Statement II are true
4. Statement I is false but Statement II is true

The Lassaigne's extract is boiled with dil HNO3 before testing for halogens because,

1. Silver halides are soluble in HNO3.
2. AgCN is soluble in HNO3.
3. Na2S and NaCN are decomposed by HNO3.
4. Ag2S is soluble in HNO3.

On a thin layer chromatographic plate, an organic compound moved by 3.5 cm, while the solvent moved by 5 cm. The retardation factor of the organic compound is 10-1.

Which among the following purification methods is based on the principle of "Solubility" in two different solvents?

1. Distillation
2. Sublimation
3. Column Chromatography
4. Differential Extraction

Number of metal ions characterized by flame test among the following is . Sr2+, Ba2+, Ca2+, Cu2+, Zn2+, Co2+, Fe2+

In chromyl chloride test for confirmation of Cl- ion, a yellow solution is obtained. Acidification of the solution and addition of amyl alcohol and 10\% H2O2 turns organic layer blue indicating formation of chromium pentoxide. The oxidation state of chromium in that is

1. +6
2. +5
3. +3
4. +10

Appearance of blood red colour, on treatment of the sodium fusion extract of an organic compound with FeSO4 in presence of concentrated H2SO4 indicates the presence of element/s

1. Br
2. S
3. N and S
4. N

On passing a gas, 'X', through Nessler's reagent, a brown precipitate is obtained. The gas 'X' is

1. Cl2
2. CO2
3. NH3
4. H2S