Temperature can change the state from solid to liquid causing it to melting, liquid to gas causing vaporization or a solid to a gas causing sublimation. Pressure alone cannot change the state of matter.
Aluminum has an atomic number of 13, so it has 13 protons. In its natural state, it does not have a charge, so it has an equal amount of electrons, 13. The atomic mass of aluminum is approximately 27. Since protons and neutrons make up that mass, and each of the particles are around 1 atomic mass unit, if there are 13 protons, then there are 27-13 neutrons, or 14 neutrons. So the first answer choice is correct.
To calculate the force between two negative charges, we use the formula which is given by the Coulomb`s Law as

Here,
and
are the charges on the pith balls, r is the separation between the charges and k is constant and its value is
.
Given
and
.
Substituting these values in above formula we get,

Thus, the repulsive force between two pith balls is
.
Explanation:
The given data is as follows.

Voltage = 2.50 V
Hence, calculate the equivalence capacitor as follows.


= 
C = 
Now, we will calculate the charge across each capacitance as follows.
Q = CV
= 
=
=
Thus, we can conclude that
is the charge stored on each given capacitor.
Answer:
The kangaroo was 1.164s in the air before returning to Earth
Explanation:
For this we are going to use the equation of distance for an uniformly accelerated movement, that is:

Where:
x = Final distance
xo = Initial point
Vo = Initial velocity
a = Acceleration
t = time
We have the following values:
x = 1.66m
xo = 0m (the kangaroo starts from the floor)
Vo = 0 m/s (each jump starts from the floor and from a resting position)
a = 9.8 m/s^2 (the acceleration is the one generated by the gravity of earth)
t =This is just the time it takes to the kangaoo reach the 1.66m, we don't know the value.
Now replace the values in the equation





It takes to the kangaroo 0.582s to go up and the same time to go down then the total time it is in the air before returning to earth is
t = 0.582s + 0.582s
t = 1.164s
The kangaroo was 1.164s in the air before returning to Earth