41.
Sound travels at the fastest speed in

42.
Oil raise up the wick in a lamp. The principle involves

43.
Superconductors are substances which

45.
Railway tracks are banked on curves

46.
On a cold day when a room temperature is 15oC, the metallic cap of a pen becomes much colder than its plastic body, though both are at the same temperature of 15oC, because

47.
Sound produced at a point is heard by a person after 5 second, while the same sound is heard by another person after 6 seconds. If the speed of sound is 300 m/s, what could be the maximum and minimum distances between the two persons?

48.
Intensity of sound at a point is ____ its distance from the source.

49.
Of the four locations mentioned below the highest inside temperature will be attained in the pressure cooker operated with the pressure valve open

50.
Radio telescopes are better than optical telescopes because