NEET Aldehydes Ketones and Carboxylic Acids — Set 17

Question 1

Which compound is produced when benzoic acid reacts with $ \ce{LiAlH4} $?

Accepted Answer

$ \ce{LiAlH4} $ reduces carboxylic acids to primary alcohols. Benzoic acid ($ \ce{C6H5COOH} $) yields benzyl alcohol ($ \ce{C6H5CH2OH} $).

Question 2

Arrange in increasing order of reactivity towards $ \ce{HCN} $: $ \ce{CH3COCH3} $, $ \ce{CH3CHO} $, $ \ce{(CH3)2CHCHO} $.

Accepted Answer

Reactivity decreases with steric hindrance: $ \ce{CH3COCH3} $ (ketone) < $ \ce{(CH3)2CHCHO} $ (branched aldehyde) < $ \ce{CH3CHO} $ (simple aldehyde).

Question 3

Which compound gives a positive 2,4-DNP test but not a Fehling’s test?

Accepted Answer

Acetophenone ($ \ce{C6H5COCH3} $) is a ketone (positive 2,4-DNP test) but does not reduce Fehling’s solution (negative Fehling’s test).

NEET Chemistry: Aldehydes Ketones and Carboxylic Acids — Practice Set 17

Q1. Which compound is produced when benzoic acid reacts with \( \ce{LiAlH4} \)?

Q2. Arrange in increasing order of reactivity towards \( \ce{HCN} \): \( \ce{CH3COCH3} \), \( \ce{CH3CHO} \), \( \ce{(CH3)2CHCHO} \).

Q3. Which compound gives a positive 2,4-DNP test but not a Fehling’s test?

Q4. Which test produces a silver mirror with pentanal but not with pentan-2-one?

Q5. Which compound does not undergo aldol condensation?

Q6. How is benzaldehyde converted to benzophenone in two steps?

Q7. Which ketone, when treated with \( \ce{SeO2} \), yields a dicarbonyl compound with five carbon atoms?

Q8. Which aldehyde forms a chiral cyanohydrin upon reaction with \( \ce{HCN} \)?

Q9. Which compound is formed by the ozonolysis of 1-butene followed by hydrolysis?

Q10. Which test produces a pink color with aldehydes but not with ketones?