Which mode to take preemptive or non preemptive

Question

If the mode for scheduling is not mentioned whether to do preemptive or non preemptive which one should we take when solving Gate questions?

Comments

Gate questions are expected to be unambiguous. Either the scheduling algo itself will indicate if it's pre-emptive or not (like SRTF, RR, LRTF are pre-emptive) or they will explicitly mention the mode or may describe an algo which will have some hint.