they have more energy than radio waves.
&
because the wavelength of the light waves are too small
Think of the formula force=mass x acceleration. even though they have the same acceleration, a train has more mass. is that helpful?
5.4 x 1014Hz
wavelength x frequency = the speed of light
The average speed of the car for the entire trip can be calculate by using:

where S is the total distance covered by the car, and t is the total time taken.
The total distance travelled by the car is:

while the total time taken is:

so, the average speed of the car is:

so, the correct answer is (3) 85 km/h.