Answer:
7 s
Explanation:
u = Initial velocity of rock = 12.2 m/s
= Angle of throw = 
x = Displacement in x direction = 25 m
Displacement in x direction is given by

Time taken to reach the ground is 7 s.
Answer:
Carbon and oxygen
Explanation:
White dwarfs are the stars which have used all their hydrogen and helium fuel and now exists with only carbon and oxygen in their core. Their size reduces up to one hundredth times of the size of their sun in early stages and yet they possess the same mass.
Due to loss of fuels and impact of gravity, a young star collapses on itself leading to formation of dwarf star.
The answer is A. subduction
I think the correct answer is B.