Calculate the Ka for 0.2M solution of hydrocyanic acid (HCN) if the pH=5

You drop a rubber ball off the roof of a 50 meter high building onto a paved parking lot. it bounces back up with every bounce, but not quite all the way back up to you. after the first bounce it bounces back only 80 percent of the distance it was dropped from. the pattern continues, meaning after every bounce it comes up to just 80 percent of the previous maximum height. so if before the first bounce the height is 50 meters, what height does the ball reach after the fifth bounce? round your answer to one decimal place and chose the correct response from the choices below:

Write the expression as a single natural logarithm. 2 in a - 4 in y

Reagan lives five miles farther from school than vanessa lives. write an expression to describe how far reagan lives from school