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. \(\mathrm{Fe}_4\left[\mathrm{Fe}(\mathrm{CN})_6\right]_3 \cdot \times \mathrm{H}_2 \mathrm{O} \)
3. \(\mathrm{NaSCN} \)
4. \(\left[\mathrm{Fe}(\mathrm{CN})_5 \mathrm{NOS}\right]^{4-} \)
Subtopic:  Qualitative Analysis of Organic Compounds |
 61%
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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NEET 2023 - Target Batch - Aryan Raj Singh
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NEET 2023 - Target Batch - Aryan Raj Singh

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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NEET 2023 - Target Batch - Aryan Raj Singh
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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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NEET 2023 - Target Batch - Aryan Raj Singh
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NEET 2023 - Target Batch - Aryan Raj Singh