M06
School-to-graduate level physics, chemistry and biology fundamentals
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Every served question is explained like this — including why each wrong option is wrong.
______ does not take part in mitotic division.
Why A is correct
Heterochromatin is the densely packed, genetically inert fraction of chromatin - it stays condensed and transcriptionally inactive, in contrast to euchromatin which carries the actively expressed genes.
An oxygen molecule is 16 times as heavy as a hydrogen molecule. The temperature of oxygen when its average speed is equal to that of hydrogen at 30 K is:
Why B is correct
Average molecular speed varies as sqrt(T/M). For the speeds to be equal, T/M must be equal for both gases, so T_oxygen = T_hydrogen x (M_oxygen/M_hydrogen) = 30 x 16 = 480 K.
If the voltage gain of an amplifier without feedback is 20 and with negative voltage feedback it is 12, then the feedback fraction is:
Why D is correct
With negative feedback, A_f = A/(1 + Aβ). Substituting 12 = 20/(1 + 20β) gives 1 + 20β = 5/3, so 20β = 2/3 and β = 1/30 ≈ 0.033.
14 questions · +2.5/−⅓ UPSC marking · explanations after every answer. No sign-up needed.