Physics
Stars twinkle because

None of these
the distance of the stars from the earth changes with time.
the refractive index of the different layers of the earth's atmosphere ch
the intensity of light emitted by them changes with time.

ANSWER DOWNLOAD EXAMIANS APP

Physics
Superconductors are those elements

Which conduct electricity only at super-high temperatures
Which turn into insulators at very low temperatures
Whose conductivity is intermediate between metals and insulators
Whose resistance falls almost to zero at very low temperatures

ANSWER DOWNLOAD EXAMIANS APP