UPSC Prelims 2025 GS Paper I · Q1 of 99 General Science easy

Consider the following types of vehicles : I. Full battery electric vehicles II. Hydrogen fuel cell vehicles III. Fuel cell electric hybrid vehicles How many of the above are considered as alternative powertrain vehicles?

  1. (a) Only one
  2. (b) Only two
  3. (c) All the three ✓ UPSC's answer
  4. (d) None

Why the answer is (c)

• 'Alternative powertrain' means any propulsion system other than the conventional petrol or diesel internal-combustion engine.

• Full battery electric vehicles run on an electric motor fed by a rechargeable battery — clearly alternative (I).

• Hydrogen fuel-cell vehicles generate electricity on board by combining hydrogen with oxygen in a fuel cell, emitting only water — alternative (II).

• Fuel-cell electric hybrids pair a fuel cell with a battery so that both supply the motor; still no combustion engine — alternative (III).

• All three count, option (c). (Petrol hybrids also qualify as alternative powertrains, but are not listed here.)

Why the other options are wrong

(a) Only one
All three, not one, are non-combustion powertrains.
(b) Only two
Fuel-cell hybrids are also alternative powertrains, so the count is three.
(d) None
Every listed type replaces the conventional engine.

Asked in the GS Paper I of the UPSC Civil Services Preliminary Examination 2025, held on 25 May 2025. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.

Reading the answer is not the same as getting it right under a clock. Practise this question with UPSC's negative marking, and anything you miss goes into an error notebook until you get it right twice.

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