Answer
given,
before collision
mass of car A = m_a = 1300 kg
velocity of car A = v_a = 35 mph
mass of car B = m_b= 1000 kg
velocity of car B = v_b = 25 mph
after collision
V_a = 30 mph
V_b = 31.5 mph
Initial momentum



final momentum



here initial momentum is equal to the final momentum of the car.
hence, momentum is conserved in the collision.
A and C is the correct one
<u>Answer:</u>
The modern atomic theory has given by "John Dalton and framed postulates".
<u>Explanation:</u>
The fundamental role of atoms in chemistry is established by the modern theory of atoms mentioned in 1808 for the first time by an English scientist named John Dalton. This consists of three sections such as all matter is composed of atoms, atoms of the same element are the same while atoms of different elements are different, atoms combine to form compounds in full-number ratios.
The unique characteristic of the "number of protons" is that all atoms of the same compound share. While the atoms of the same element i.e having a similar number of protons can have different numbers of neutrons and such elements are called isotopes.
PART a)
here when stone is dropped there is only gravitational force on it
so its acceleration is only due to gravity
so we will have

Part b)
Now from kinematics equation we will have

now we have
y = 25 m
so from above equation


Part c)
If we throw the rock horizontally by speed 20 m/s
then in this case there is no change in the vertical velocity
so it will take same time to reach the water surface as it took initially
So t = 2.26 s
Part D)
Initial speed = 20 m/s
angle of projection = 65 degree
now we have




PART E)
when stone will reach to maximum height then we know that its final speed in y direction becomes zero
so here we can use kinematics in Y direction



so it will take 1.85 s to reach the top