Principles Related to Practical Chemistry

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

Chromatographic technique/s based on the principle of differential adsorption is / are Choose the most appropriate answer from the options given below:

1. B only
2. A only
3. A & B only
4. C only

A reagent which gives brilliant red precipitate with Nickel ions in basic medium is

1. dimethyl glyoxime
2. sodium nitroprusside
3. meta-dinitrobenzene
4. neutral FeCl3

The oxidation number of iron in the compound formed during brown ring test for NO3- ion is .