Principles Related to Practical Chemistry

Consider the following reactions. (Hot solution)PbCl2 + K2CrO4 A + 2KCl A + NaOH B + Na2CrO4 PbSO4 + 4CH3COONH4 (NH4)2SO4 + X In the above reactions, A, B and X are respectively.

1. Na2[Pb(OH)2], PbCrO4 and [Pb(NH3)4]SO4
2. Na2[Pb(OH)2], PbCrO4 and (NH4)2[Pb(CH3COO)4]
3. PbCrO4, Na2[Pb(OH)4] and (NH4)2[Pb(CH3COO)4]
4. PbCrO4, Na2[Pb(OH)4] and [Pb(NH3)4]SO4

In Carius method, 0.75 g of an organic compound gave 1.2 g of barium sulphate, find percentage of sulphur (molar mass 32 g mol-1). Molar mass of barium sulphate is 233 g mol-1.

1. 4.55%
2. 16.48%
3. 10.30%
4. 21.97%

On heating a mixture of common salt and K2Cr2O7 in equal amount along with concentrated H2SO4 in a test tube, a gas is evolved. Formula of the gas evolved and oxidation state of the central metal atom in the gas respectively are:

1. Cr2O2Cl2 and +3
2. Cr2O2Cl2 and +6
3. CrO2Cl2 and +6
4. CrO2Cl2 and +5

By usual analysis, 1.00 g of compound (X) gave 1.79 g of magnesium pyrophosphate. The percentage of phosphorus in compound (X) is : (nearest integer) (Given, molar mass in g mol-1: O = 16, Mg = 24, P = 31)

1. 40
2. 30
3. 20
4. 50

On combustion 0.210 g of an organic compound containing C, H and O gave 0.127 g H2O and 0.307 g CO2. The percentages of hydrogen and oxygen in the given organic compound respectively are:

1. 7.55, 43.85
2. 6.72, 53.41
3. 6.72, 39.87
4. 53.41, 39.6

Match the LIST-I with LIST-II Choose the correct answer from the options given below:

1. A-II, B-III, C-I, D-IV
2. A-II, B-IV, C-III, D-I
3. A-III, B-II, C-IV, D-I
4. A-II, B-III, C-IV, D-I

When a salt is treated with sodium hydroxide solution it gives gas X. On passing gas X through reagent Y a brown coloured precipitate is formed. X and Y respectively, are

1. X = NH3 and Y = HgO
2. X = NH4Cl and Y = KOH
3. X = NH3 and Y = K2HgI4 + KOH
4. X = HCl and Y = NH4Cl

An organic compound weighing 500 mg, produced 220 mg of CO2, on complete combustion. The percentage composition of carbon in the compound is %. (nearest integer) (Given molar mass in g mol-1 of C : 12, O : 16)

A mixture of 1 g each of chlorobenzene, aniline, and benzoic acid is dissolved in 50 mL ethyl acetate and placed in a separating funnel. 5 M NaOH (30 mL) was added in the same funnel. The funnel was shaken vigorously and then kept aside. The ethyl acetate layer in the funnel contains :

1. chlorobenzene and aniline
2. benzoic acid and aniline
3. benzoic acid
4. benzoic acid and chlorobenzene

In Dumas' method 292 mg of an organic compound released 50 mL of nitrogen gas (N2) at 300 K temperature and 715 mm Hg pressure. The percentage composition of 'N' in the organic compound is % (Nearest integer) (Aqueous tension at 300 K = 15 mm Hg)