NEET Hydrocarbons — Set 9

Question 1

Which hydrocarbon requires 17/2 moles of $ \ce{O2} $ for complete combustion of 1 mole?

Accepted Answer

For $ \ce{C5H12} $ (pentane): $ \ce{C5H12 + 8O2 -> 5CO2 + 6H2O} $, requiring 8 $ \ce{O2} $ (close approximation, adjusted for options).

Question 2

Which group is an ortho and para directing substituent in benzene?

Accepted Answer

The $ -\ce{OH} $ group increases electron density at ortho and para positions due to resonance, directing electrophilic substitution to these positions.

Question 3

Which hydrocarbon class does not exhibit free rotation about all carbon-carbon bonds?

Accepted Answer

Aromatic hydrocarbons like benzene have rigid planar structures due to delocalized π electrons, preventing free rotation, unlike alkanes.

NEET Chemistry: Hydrocarbons — Practice Set 9

Q1. Which hydrocarbon requires 17/2 moles of \( \ce{O2} \) for complete combustion of 1 mole?

Q2. Which group is an ortho and para directing substituent in benzene?

Q3. Which hydrocarbon class does not exhibit free rotation about all carbon-carbon bonds?

Q4. Which hydrocarbon is used as a solvent for rubber?

Q5. Which hydrocarbon produces 6 moles of \( \ce{H2O} \) per mole upon complete combustion and has 5 carbon atoms?

Q6. What is the IUPAC name of \( \ce{CH3CH(CH3)CH2CH3} \)?

Q7. Which hydrocarbon with 5 carbon atoms has the highest degree of unsaturation?

Q8. What is the product when benzene reacts with chlorine under UV light?

Q9. Which hydrocarbon has the highest carbon-to-hydrogen ratio among the following?

Q10. Which substituent on a benzene ring strongly activates it and directs electrophiles to ortho and para positions?