Principles Related to Practical Chemistry

During Lassaigne's test, the elements present in an organic compound are converted from :

1. Ionic form to ionic form
2. Covalent form to ionic form
3. Ionic form to covalent form
4. Covalent form to covalent form

The functional group that can be identified through phthalein dye test is :

1. Carboxylic acid
2. Alcohol
3. Aldehyde
4. Phenolic

Phenolphthalein is used as an indicator for the titration of sodium hydroxide solution against a standard solution of oxalic acid. The colour change that is observed at an alkaline pH close to the equivalence point during this titration is :

1. pink to colourless
2. pinkish red to yellow
3. colourless to pink
4. yellow to pinkish red

Two products X and Y are formed in the following reaction sequence. [figure] The suitable method that can be used for the separation of products X and Y is :

1. Continuous extraction
2. Differential extraction
3. Sublimation
4. Fractional distillation

In a test tube containing a salt, a few drops of dilute H2SO4 was added, which gave colourless vapours having the smell of vinegar. The vapours turned the blue litmus paper red. Identify the correct anion from the following :

1. Carbonate, CO32-
2. Sulphide, S2-
3. Acetate, CH3COO-
4. Sulphate, SO42-

In potash alum, the ratio of K+ and SO42- ions is

1. 3 : 2
2. 1 : 2
3. 2 : 1
4. 2 : 3

Which one of the following reactions does NOT belong to "Lassaigne's test"?

1. Na + X NaX
2. 2CuO + C 2Cu + CO2
3. Na + C + N NaCN
4. 2Na + S Na2S

On heating, some solid substances change from solid to vapour state without passing through liquid state. The technique used for the purification of such solid substances based on the above principle is known as

1. Crystallization
2. Sublimation
3. Distillation
4. Chromatography

During the preparation of Mohr's salt solution (Ferrous ammonium sulphate), which of the following acid is added to prevent hydrolysis of Fe2+ ion?

1. dilute hydrochloric acid
2. concentrated sulphuric acid
3. dilute nitric acid
4. dilute sulphuric acid

Given below are certain cations. Using inorganic qualitative analysis, arrange them in increasing group number from 0 to VI. Choose the correct answer from the options given below.

1. B, A, D, C, E
2. B, C, A, D, E
3. E, C, D, B, A
4. E, A, B, C, D

Which indicator is used in the titration of sodium hydroxide against oxalic acid and what is the colour change at the end point?

1. Phenolphthalein, pink to yellow
2. Alkaline KMnO4, colourless to pink
3. Phenolphthalein, colourless to pink
4. Methyl orange, yellow to pinkish red colour

A steam volatile organic compound which is immiscible with water has a boiling point of 250 C. During steam distillation, a mixture of this organic compound and water will boil :

1. above 100 C but below 250 C
2. above 250 C
3. at 250 C
4. close to but below 100 C

On complete combustion, 0.3 g of an organic compound gave 0.2 g of CO2 and 0.1 g of H2O. The percentage composition of carbon and hydrogen in the compound, respectively is:

1. 4.07% and 15.02%
2. 18.18% and 3.70%
3. 15.02% and 4.07%
4. 3.70% and 18.18%

In Lassaigne's extract of an organic compound, both nitrogen and sulphur are present, which gives blood red colour with Fe3+ due to the formation of-

1. NaSCN
2. [Fe(CN)5NOS]4-
3. [Fe(SCN)]2+
4. Fe4[Fe(CN)6]3 xH2O

The Kjeldahl's method for the estimation of nitrogen can be used to estimate the amount of nitrogen in which one of the following compounds?

1. [figure]
2. [figure]
3. [figure]
4. [figure]

Paper chromatography is an example of :

1. Partition chromatography
2. Thin layer chromatography
3. Column chromatography
4. Adsorption chromatography

The most suitable method of separation of 1 : 1 mixture of ortho and para-nitrophenols is

1. chromatography
2. crystallisation
3. steam distillation
4. sublimation.

In Dumas method for estimation of nitrogen, 0.25 g of an organic compound gave 40 mL of nitrogen collected at 300 K temperature and 725 mm pressure. If the aqueous tension at 300 K is 25 mm, the percentage of nitrogen in the compound is

1. 16.75
2. 15.76
3. 17.36
4. 18.20

In the Kjeldahl's method for estimation of nitrogen present in a soil sample, ammonia evolved from 0.75 g of sample neutralized 10 mL of 1 M H2SO4. The percentage of nitrogen in the soil is

1. 37.33
2. 45.33
3. 35.33
4. 43.33

Nitrogen detection in an organic compound is carried out by Lassaigne's test. The blue colour formed corresponds to which of the following formulae?

1. Fe3[Fe(CN)6]2
2. Fe4[Fe(CN)6]3
3. Fe4[Fe(CN)6]2
4. Fe3[Fe(CN)6]3

The Lassaigne's extract is boiled with conc. HNO3 while testing for halogens. By doing so it

1. decomposes Na2S and NaCN, formed
2. helps in the precipitation of AgCl
3. increases the solubility product of AgCl
4. increases the concentration of NO3- ions

In Dumas method of estimation of nitrogen, 0.35 g of an organic compound gave 55 mL of nitrogen collected at 300 K temperature and 715 mm pressure. The percentage composition of nitrogen in the compound would be (aqueous tension at 300 K = 15 mm).

1. 15.45
2. 16.45
3. 17.45
4. 14.45

The best method for the separation of naphthalene and benzoic acid from their mixture is

1. distillation
2. sublimation
3. chromatography
4. crystallisation.

Which of the following is incorrect?

1. FeCl3 is used in detection of phenol.
2. Fehling's solution is used in detection of glucose.
3. Tollens' reagent is used in detection of unsaturation.
4. NaHSO3 is used in detection of carbonyl compound.

In steam distillation of toluene, the pressure of toluene in vapour is

1. equal to pressure of barometer
2. less than pressure of barometer
3. equal to vapour pressure of toluene in simple distillation
4. more than vapour pressure of toluene in simple distillation.