Principles Related to Practical Chemistry

During the detection of acidic radical present in a salt, a student gets a pale yellow precipitate soluble with difficulty in NH4OH solution when sodium carbonate extract was first acidified with dil. HNO3 and then AgNO3 solution was added. This indicates presence of :

1. I-
2. CO32-
3. Cl-
4. Br-

The correct statement among the following, for a "chromatography" purification method is :

1. Rf of a polar compound is smaller than that of a non-polar compound.
2. Non-polar compounds are retained at top and polar compounds come down in column chromatography.
3. Organic compounds run faster than solvent in the thin layer chromatographic plate.
4. Rf is an integral value.

Consider the following reactions NiS + HNO3 + HCl A + NO + S + H2O [figure] The number of protons that do not involve in hydrogen bonding in the product B is .

[figure] In a borax bead test under hot condition, a metal salt (one from the given) is heated at point B of the flame, resulted in green colour salt bead. The spin-only magnetic moment value of the salt is BM (Nearest integer) [Given atomic number of Cu = 29, Ni = 28, Mn = 25, Fe = 26]

While preparing crystals of Mohr's salt, dil H2SO4 is added to a mixture of ferrous sulphate and ammonium sulphate, before dissolving this mixture in water, dil H2SO4 is added here to :

1. prevent the hydrolysis of ferrous sulphate
2. prevent the hydrolysis of ammonium sulphate
3. increase the rate of formation of crystals
4. make the medium strongly acidic

Using the given figure, the ratio of Rf values of sample A and sample C is x 10-2. Value of x is . [figure]

In the precipitation of the iron group (III) in qualitative analysis, ammonium chloride is added before adding ammonium hydroxide to :

1. decrease concentration of -OH ions
2. increase concentration of Cl- ions
3. prevent interference by phosphate ions
4. increase concentration of NH4+ ions

Which of the following nitrogen containing compound does not give Lassaigne's test ?

1. Glycine
2. Phenyl hydrazine
3. Urea
4. Hydrazine

When MnO2 and H2SO4 are added to a salt (A), a greenish yellow gas is liberated. The salt (A) is :

1. NH4Cl
2. CaI2
3. KNO3
4. NaBr

The adsorbent used in adsorption chromatography is/are - Choose the most appropriate answer from the options given below :

1. C and D only
2. A only
3. B only
4. A and B only