Abus slows down uniformly from 75.0 km/h ( 21 m/s) to 0 km/h in 21 s. how far does it travel before stopping

In this question two important things are already given . Let us first note them down first.
Speed of the bus = 75.0 km/hr or 21/s
Time before it finally stops = 21second.
It is better to calculate in miles per second as the time given is in second. This will make the problem easier.
We already know that
Distance traveled = Speed * time
                             = 21 * 21 meters
                             = 441 meters
So the bus will stop after traveling a distance of 441 meters.
This distance can be converted to kilometer as well very easily now.
1000 meter = 1 km
441 meters = 441/1000 km
                   = 0.441 km
So the bus will stop after 441 meters or 0.441 kilometers.

The answer is water molecules are split.cellular respiration and photosynthesis are complement  reactions to each other. these are reverse reactions. in cellular respiration glucose and oxygen yield water and carbon dioxide. so, when respiration begins,  glucose molecules are split. in the opposite reaction - in photosynthesis, carbon dioxide and water yield glucose and oxygen. thus,  when respiration begins, water molecules are split.