With the help clues provided in the image, can you find the 5 digit key?

A train leaves from point A for point B at 80 mph. After half an hour, another train leaves from point B for point A at 60 mph.

Which of the trains will be farther from point A when they meet ?

You need to complete the maze by entering from the entrance marked below in the figure near the yellow circle, bottom left and leaving from the exit point near the green circle, bottom middle.

Rule of Game: You can move only by exchanging green and yellow circles.

A tree doubled in height each year until it reached its maximum height over the course of ten years. How many years did it take for the tree to reach half its maximum height?

You have 10 balls with you. A friend of yours out of nowhere asks you to place those ten balls in five lines such that each of the lines has exactly 4 balls on them. He needs to check your intelligence. Prove him by doing the task.

What do you get if you add 2 to 100 four times?

Replace The Question Mark Below With the Correct Number.

2 {38} 3
4 {1524} 5
6 {3548} 7
8 {????} 9

Which statement is true out of the following?
One statement here is false.
Two statements here are false.
Three statements here are false.

Replace the question mark with the correct number below.

Decode below rebus
D
N
A
T
S , D