Answer
Same, doubles, changes in another way.
Work Step by Step
a. The time in the air stays the same, because the initial vertical velocity and vertical position are unchanged, and those determine the time in the air.
b. Because the book’s horizontal velocity doubles, but the time stays the same, the horizontal distance traveled also doubles.
c. The speed of the book upon landing equals the square root of the sum of the squares of the velocity components upon landing. The vertical component stays the same, but the horizontal component doubles. The speed of the book upon landing neither stays the same nor doubles; it changes in another way.
