Answer:
The minimum difference between the lengths of the two tubes should be 0.385 meters.
Explanation:
As we known that for any two waves to arrive in phase at any point the difference in the path traveled by the waves should be an integral multiple of the wavelength of the wave.
Mathematically we can write:

For the given wave we have

Applying values we get

Thus the minimum difference in the lengths of the tubes can be obtained by putting the value of n = 1

Do you mean what order the Earth is in? The planets in order from closest to farthest from the sun are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto is technically just a dwarf planet but I'll include it anyways.
Answer:
it change speed
Explanation:
its because when light passes through one medium to another (rarer to denser)its velocity change and its speed also changes