What is the relationship between the strength of a bond (single vs double vs triple) and its wave-number on an IR spectrum? As the bond strength increases the wave number increases. As the bond strength increases the wave number decreases. As the bond strength decreases the wave number increases. Wave number is highest for double bonds and lowest for single and triple bonds. There is no relationship.

d.7.5cm is your answer

wavelength divides in half and speed stays the same.

when two balls of the different masses are dropped from equal height, they reach the ground at the same time .this is because they experience the same acceleration.

the acceleration is independent of mass.

thus when they are dropped they will always maintain the same velocity and travel the same distance (neglect air resistance of course) at the same time.