Question

An automobile engine fuel has cetane number of 80. Which of the following statement is/are true?

(A) Fuel contain 80% of α–methyl naphthalene and 20% of C₁₆H₃₄ 

(B) Fuel contains 80% of cetane and 20% of a–methyl naphthalene

(C) Knocking property of the given fuel compared to the knocking property of a fuel with cetane number of 90 is high

(D) Cetane number determines the quality of diesel fuel in terms of ignition properties

Answer 1

Correct option  (B , D)

Explanation:

A. Wrong (by the definition of cetane number).\

B. True (by the definition of cetane number).

C. Wrong (higher cetane number means higher percentage of straight –chain hydrocarbon (C₁₆H₃₂), whose knocking property is high). Therefore, cetane number of 90 has high knocking property (makes more rattling sound).

D. True (cetane number determines the quality of diesel fuel in terms of spontaneous ignition). Higher cetane number means that fuel ignites faster but makes more rattling sound (i.e., more knocking).