This set of Engineering Chemistry Multiple Choice Questions & Answers (MCQs) focuses on “Anti Knocking Agents – 2”.
1. Why is cresyl diphenyl phosphate added with petrol?
a) To increase the inductance period of the engine
b) To decrease the electrical conductivity of lead compounds
c) To increase the electrical conductivity of lead compounds
d) To decrease the inductance period of the engine
Explanation: Due to high traffic in cities, sometimes lead is not removed properly by ethylene dibromide. Due to this condition cresyl diphenyl phosphate is added with petrol, so that it can reduce the electrical conductivity of the lead compounds deposited on the spark plug points.
2. Which type of octane rating of petrol is used in India?
d) Octane- 87
Explanation: Before 1983 the petrol of octane rating 83 was used, while after September 1983 the petrol of octane rating 87 is used. The increase in the petrol prices is due to the shortage of crude oil.
3. How much power output can be achieved by using fuel of octane rating 100?
a) 21.3 %
b) 10.5 %
c) 26.7 %
d) 35.9 %
Explanation: If the compression ratio is suitably adjusted, an increase in octane number from 73 to 100 increases the power output by 26.7 % and reduces the fuel consumption by 29 %. However, there is no practical advantage of using fuel of high octane number.
4. What amount of lead is permissible for unleaded gasoline in India?
a) 13 mg/L
b) 17 mg/L
c) 21 mg/L
d) 10 mg/L
Explanation: With the introduction of catalytic converters, unleaded gasoline was introduced in India. If the lead concentration is less than 13 mg/L, then the gasoline is practically considered containing zero quantity of lead.
5. What happens when noble metals like platinum and palladium are used as a catalyst in catalytic converters?
a) They convert the hydrocarbon content into CO2 and H2O
b) They reduce NOx emissions
c) They prone to poisoning by lead
d) They are used to decrease lead content in gasoline
Explanation: Catalyst made of noble metals like platinum and palladium are prone to poisoning by lead and also they are very expensive. Catalytic converter ae used to decrease the amount of lead present in gasoline. Using this type of catalyst it can reverse the reaction.
6. Which of the following does the catalytic converter consist for reduction of emissions from petrol driven vehicles?
a) Non-metal support
b) Ceramics support
c) Gels and sols support
d) Radioactive element support
Explanation: The catalytic converter consists of ceramic or metallic honeycomb support coated with a propriety low cost catalyst, housed in a suitably designed non-corrosive metallic housing. This catalytic converter was developed by NEERI, Nagpur.
7. Which of the following element has low toxicity than lead which can be used as anti-knocking agent, when released into environment?
Explanation: In environment manganese is released as Mn3O4 which is a less toxic gas then lead bromide. Manganese is considered as a biologically essential element. Methylcyclopentienyl manganese tricarbonyl (MMT) can be used in place of TEL as an anti-knocking agent.
8. Anti-knocking agent MMT is found to be toxic if ingested or inhaled.
Explanation: MMT is environmentally friendly, but it causes fouling of spark plugs and on board sensors. It causes internal problems, if ingested or is inhaled. It does reduces knocking in the engine.
9. How can we alter the hydrocarbon molecules in crude oil?
a) By fractional distillation
b) By alkylation
c) By pulverising method
d) By heating
Explanation: Modern petroleum refineries have the capability to alter the hydrocarbon molecules in the crude oil by cracking, alkylation and reforming processes. Knocking can be reduced by increasing the fraction of high octane compounds.
10. Which of the following aromatic compound has a greater potential to smog formation?
Explanation: By increasing the concentration of aromatic hydrocarbons, the knocking can be reduced to a certain level. Xylene on combustion gives rise to a lot of smoke which on mixing with fog in winter season forms smog which causes many respiratory diseases.
Sanfoundry Global Education & Learning Series – Engineering Chemistry.
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