Star 1 - 4 hours right ascension
Star 2 - 3 hours right ascension
Subtracting hours right ascension
4 hours right ascension - 3 hours right ascension = 1 hours right ascension.
Thus,
star 1 will rise 1 hour before star 2
Physical changes: melting, evaporating, and condensation. This is a physical change.
I think your answer would be DDT, but don't hold me to it
O2 refers to two oxygen atoms bonded together, while 2 O refers to two oxygen atoms that are not bonded to each other. They both have two oxygen atoms, but in O2, the oxygen atoms are bonded, while in 2O, the atoms are not.
Answer:
The velocity of the ball when its hit the ground will be 54.22 m/sec
Explanation:
We have given height from which ball is dropped h = 150 m
Acceleration due to gravity 
As the ball is dropped so initial velocity will be zero so u = 0 m/sec
According to third equation of motion we know that 


So the velocity of the ball when its hit the ground will be 54.22 m/sec