Principles Related to Practical Chemistry · Question 30

When 1 g of compound (X) is subjected to Kjeldahl's method for estimation of nitrogen, 15 mL 1 M H2SO4 was neutralized by ammonia evolved. The percentage of nitrogen in compound (X) is :

1. 0.21
2. 21
3. 42
4. 0.42

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