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. Sublimation
2. Distillation
3. Chromatography
4. Crystallization
Subtopic:  Qualitative Analysis of Organic Compounds |
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From NCERT
NEET - 2024
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The method used for quantitative estimation of halogens is:
1. Dumas method 2. Carius method
3. Kjeldahl's method 4. Combustion method
Subtopic:  Qualitative Analysis of Organic Compounds |
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From NCERT
NEET - 2024
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The technique used to purify liquids having high boiling points and getting decomposed at or below their boiling points is:

1. Fractional distillation 
2. Steam distillation
3. Simple distillation
4. Distillation under reduced pressure
Subtopic:  Qualitative Analysis of Organic Compounds |
 62%
From NCERT
NEET - 2024
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The compound that gives blood red colour in Lassaigne's test is:
1.
2.
3.
4.

 
Subtopic:  Qualitative Analysis of Organic Compounds |
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From NCERT
NEET - 2024
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A steam volatile organic compound which is immiscible with water has a boiling point of \(250^\circ \text{C}\). During steam distillation, a mixture of this organic compound and water will boil:

1. Above \(100^\circ \text{C}\) but below \(250^\circ \text{C}\).
2. Above \(250^\circ \text{C}\).
3. At \(250^\circ \text{C}\).    
4. Close to but below \(100^\circ \text{C}\).
Subtopic:  Qualitative Analysis of Organic Compounds |
From NCERT
NEET - 2024
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In Lassaigne's extract of an organic compound, both nitrogen and sulphur are present, which gives blood red colour with \(\text{Fe}^{3+}\) due to the formation of:

1. \([\mathrm{Fe}(\mathrm{SCN})]^{2+} \)
2. \(\mathrm{Fe}_4\left[\mathrm{Fe}(\mathrm{CN})_6\right]_3 \cdot \mathrm{xH}_2 \mathrm{O} \)
3. \(\mathrm{NaSCN} \)
4. \(\left[\mathrm{Fe}(\mathrm{CN})_5 \mathrm{NOS}\right]^{4-} \)
Subtopic:  Qualitative Analysis of Organic Compounds |
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From NCERT
NEET - 2023
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The most suitable method used for the separation of 1:1 mixture of ortho and para-nitrophenols is:

1. Chromatography 2. Crystallization
3. Steam distillation 4. Sublimation
Subtopic:  Qualitative Analysis of Organic Compounds |
 79%
From NCERT
NEET - 2017
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In Kjeldahl’s method for estimation of nitrogen present in the soil sample, ammonia evolved from 0.75g of sample neutralized 10ml. of 1M H2SO4. The percentage of nitrogen in the soil is:

1. 37.33 2. 45.85
3. 25.75 4. 43.13
Subtopic:  Qualitative Analysis of Organic Compounds |
 71%
From NCERT
AIPMT - 2014
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The Lassaigne’s extract is boiled with conc. HNO3 while testing for halogens, because it:

1. Helps in the precipitation of AgCl
2. Increases the solubility product of AgCl
3. Increases the concentration of NO3- ions
4. Decomposes Na2S and NaCN, if formed

Subtopic:  Qualitative Analysis of Organic Compounds | Quantitative Analysis of Organic Compounds |
 71%
From NCERT
AIPMT - 2011
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