JAMB Chemistry 2019 Objective — Question 17
Question 17 of 40 from the Joint Admissions and Matriculation Board (JAMB) Chemistry 2019 Objective paper, with the correct answer and a full explanation.
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An alkanoic acid has a molar mass of 102gmol⁻¹. Derive its name.
- A. Hexanoic acid
- B. pentanoic acidCorrect
- C. Butanoic acid
- D. propanoic acid
Explanation
General formula of alkanoic acids: CₙH₂ₙ₊₁COOH. With molar mass 102: 12n+(2n+1)+12+16+16+1=102 ⇒ 14n+46=102 ⇒ n=4. Substituting n=4 gives C₄H₉COOH — pentanoic acid. (Note: the source's key letter for this item was recorded as D, but its own derivation concludes pentanoic acid, matching option B — flagged as a possible letter/key mismatch in the source.)
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