Answer:
Option A
Carrots are cut into small pieces and mixed into a salad
Explanation:
When physical changes occur, the actual composition remain the same but the molecules are re-arranged. Therefore, when carrots are cut into smaller pieces and mixed into salad, there will be no chemical reaction hence the actual composition will remain the same despite being cut and molecules in it re-arranged. Considering the other options, new substances are formed hence they are deemed as chemical changes. Therefore, option A is correct.
Answer:

Explanation:
It is given that,
Mass of the baseball, m = 0.14 kg
It is dropped form a height of 1.8 m above the ground. Let u is the velocity when it hits the ground. Using the conservation of energy as :

h = 1.8 m

u = 5.93 m/s
Let v is the speed of the ball when it rebounds. Again using the conservation of energy to find it :

h' = 1.4 m

v = -5.23 m/s
The change in the momentum of the ball is given by :



So, the change in the ball's momentum occurs when the ball hits the ground is 1.56 kg-m/s. Hence, this is the required solution.
Answer:
b. 46 km/hr
Explanation:
Applying,
S' = d'/t'................... Equation 1
Where S' = Average speed of the bus, d' = Total distance covered by the bus, t' = Total time taken.
From the question,
d' = (100+55+75) km = 230 km
t' = (2+1+2) = 5 hours
Substitute these values into equation 1
S' = 230/5
S' = 46 km/hr.
Hence the correct option is b. 46 km/hr