NEET Organic Chemistry Some Basic Principles and Techniques — Set 10

Question 1

A hydrocarbon with 8 $ \sigma $ bonds and 2 $ \pi $ bonds undergoes complete combustion to produce 3 moles of $ \ce{CO2} $ per mole of compound. What is its molecular formula?

Accepted Answer

3 carbons (from 3 $ \ce{CO2} $). $ \ce{CH3C#CH} $ has 8 $ \sigma $ (6 C-H, 1 C-C, 1 from C≡C) and 2 $ \pi $ (C≡C), and is $ \ce{C3H4} $, producing 3 $ \ce{CO2} $ on combustion.

Question 2

A mixture of two liquids with boiling points 75°C and 90°C is separated efficiently on a large scale using which technique?

Accepted Answer

A 15°C difference (< 25°C) requires fractional distillation for efficient large-scale separation due to close boiling points.

Question 3

In the Carius method, 0.6 g of a compound gave 0.717 g of $ \ce{AgI} $. What is the percentage of iodine?

Accepted Answer

Molar mass of $ \ce{AgI} = 235 $ g/mol, I = 127 g/mol. Mass of I = $ \frac{127}{235} \times 0.717 \approx 0.387 $ g. Percentage = $ \frac{0.387}{0.6} \times 100 \approx 64.5\% $, which rounds to 64%.

NEET Chemistry: Organic Chemistry Some Basic Principles and Techniques — Practice Set 10

Q1. A hydrocarbon with 8 \( \sigma \) bonds and 2 \( \pi \) bonds undergoes complete combustion to produce 3 moles of \( \ce{CO2} \) per mole of compound. What is its molecular formula?

Q2. A mixture of two liquids with boiling points 75°C and 90°C is separated efficiently on a large scale using which technique?

Q3. In the Carius method, 0.6 g of a compound gave 0.717 g of \( \ce{AgI} \). What is the percentage of iodine?

Q4. Which purification technique is most suitable for separating a mixture of \( \ce{CHCl3} \) (b.p. 61°C) and \( \ce{CH3COCH3} \) (b.p. 56°C)?

Q5. In Dumas method, 0.4 g of a compound gave 60 mL of \( \ce{N2} \) at STP. What is the percentage of nitrogen?

Q6. Which species is least likely to act as an electrophile in a reaction with \( \ce{CH3CH=CH2} \)?

Q7. Which carbon in \( \ce{CH2=CHCH2OH} \) is \( sp^3 \) hybridized?

Q8. How many structural isomers are possible for \( \ce{C5H12} \)?

Q9. Which intermediate is least stable when formed from \( \ce{CH3CH2CH2CH3} \) via homolytic cleavage?

Q10. Which technique is used to separate colored components of a mixture based on their \( R_f \) values?