NEET Organic Chemistry Some Basic Principles and Techniques — Set 5

Question 1

What is the hybridization of the central carbon in $ \ce{CH3CH2CH3} $?

Accepted Answer

In $ \ce{CH3CH2CH3} $ (propane), the central carbon has four single bonds (two to C, two to H), indicating $ sp^3 $ hybridization.

Question 2

In Kjeldahl’s method, 0.42 g of a compound produced ammonia that neutralized 15 mL of 0.2 M $ \ce{H2SO4} $. What is the percentage of nitrogen?

Accepted Answer

Moles of $ \ce{H2SO4} $ = $ 0.015 \times 0.2 = 0.003 $. Moles of $ \ce{NH3} $ = 0.006 (2H per $ \ce{H2SO4} $). Mass of N = $ 0.006 \times 14 = 0.084 $ g. Percentage = $ \frac{0.084}{0.42} \times 100 = 20\% $.

Question 3

A hydrocarbon with a degree of unsaturation of 2 produces 4 moles of $ \ce{CO2} $ per mole upon complete combustion. What is its molecular formula?

Accepted Answer

4 carbons (from 4 $ \ce{CO2} $). Degree of unsaturation = 2 suggests two double bonds or one triple bond. $ \ce{CH3C#CCH3} $ (but-2-yne, $ \ce{C4H6} $) fits with 2 $ \pi $, 8 $ \sigma $, and 4 $ \ce{CO2} $.

NEET Chemistry: Organic Chemistry Some Basic Principles and Techniques — Practice Set 5

Q1. What is the hybridization of the central carbon in \( \ce{CH3CH2CH3} \)?

Q2. In Kjeldahl’s method, 0.42 g of a compound produced ammonia that neutralized 15 mL of 0.2 M \( \ce{H2SO4} \). What is the percentage of nitrogen?

Q3. A hydrocarbon with a degree of unsaturation of 2 produces 4 moles of \( \ce{CO2} \) per mole upon complete combustion. What is its molecular formula?

Q4. Which purification technique is used to separate a mixture of two miscible liquids with close boiling points?

Q5. In Lassaigne’s test, the presence of bromine forms a precipitate of what color with silver nitrate?

Q6. In Lassaigne’s test, an organic compound gives a violet color with sodium nitroprusside and a white precipitate with silver nitrate. What elements are present?

Q7. Which technique is least effective for separating a mixture of two liquids with boiling points of 110°C and 150°C, one of which is water-soluble?

Q8. A compound with 9 \( \sigma \) bonds and 1 \( \pi \) bond has a molecular formula of \( \ce{C4H6} \). Which carbon has a bond angle closest to 109.5°?

Q9. Which carbon in \( \ce{CH3CH2CH2C(=O)OCH3} \) has the greatest s-character in its hybridization?

Q10. Which compound with \( \ce{C4H8} \) has a degree of unsaturation of 1 and can be separated from its chain isomer by simple distillation?