Wireless transmission can be done via any of the Infrared waves, Radio waves or Microwaves.

Total distance = 150 + 210 = 360 mts

Time taken to cross each other when moving in opposite direction = 10.8 sec

Relative speed of trains = (350/10.8) x 18/5 = 3600/30 = 120 kmph

Speed of shorter train = (150/12) x 18/5 = 45 kmph

Hence, speed of longer train = 120 - 45 = 75 kmph.

A Sound wave needs a medium for propogation. Hence, Sound cannot travel through a vacuum.

A vacuum is an area without any air, like space. So sound cannot travel through space because there is no matter for the vibrations to work in.

Nitrogenous base: A molecule that contains nitrogen and has the chemical properties of a base.

DNA and RNA ::

The nitrogenous bases in DNA are

Adenine (A),

Guanine (G),

Thymine (T), and

Cytosine (C).

Whereas the nitrogenous bases in RNA are the same, with one exception:

Adenine (A),

Guanine (G),

Uracil (U), and

Cytosine (C).