Question

An automobile engine fuel has cetane number of 80. Which of the following statements is/are true ?
A. (a) Fuel contains `80%` of `alpha`-methyl naphthalene and `20%` of `C_(16)H_(34)` .
B. (b) Fuel contains `80%` of centane and `20%` of `alpha`-methyl naphthalene.
C. (c) Knocking property of the given fuel compared to the knocking property of a fuel with cetane number of 90 is high.
D. (d) Centane number determines the quality of diesel fuel in terms of ignition properties.

Answer 1

Correct Answer - B::D
a. Wrong (by the definition of centane numer).
b. True (by the definition of centance number).
Wrong (higher cetane number means higher percentage of straight-chain hydrocarbon `(C_(16H_(32))`, whose knocking propperty is high). Therefore, cetane number of 90 has high knocking property (make more rattling sound).
d. True (cetane number determines the quality of diesel fuel in terms of spontaneous ignition). Higher centane number means that ignites faster but makes more ratting sound (i.e., more knockiing).