The answer is d hope this helps
Are you referring to the fact that water is a compound while hydrogen is an element? If I'm wrong just comment and clarify and I can edit it, I don't even know what kind of unit you're in. :)
Answer:

Explanation:
As we know that
velocity of bike = 7.5 m/s
velocity of car is 10 m/s
deceleration of car is 0.75 m/s^2
part a)
velocity of bike with respect to car is given as

acceleration of bike with respect to car is given as

now the distance of the bike with respect to car is given as



Part b)
Answer:
option "c"
Explanation:
because in gases molecules are further apart and move very quickly
For me: WASH OUR HANDS REGULARLY