The density of the material would be
25/6 grams per cm^3.
to obtain the result above this is what we do:
density is calculated as: (the mass of the given material or object) / volume of the material
which leads us to 50grams /12cm^3
(a) 
The change in energy of the transferred charge is given by:

where
q is the charge transferred
is the potential difference between the ground and the clouds
Here we have


So the change in energy is

(b) 7921 m/s
If the energy released is used to accelerate the car from rest, than its final kinetic energy would be

where
m = 950 kg is the mass of the car
v is the final speed of the car
Here the energy given to the car is

Therefore by re-arranging the equation, we find the final speed of the car:

<h3><u>Answer;</u></h3>
= 0.0000001 mol/L
= 0.0000001 mol/L
= 1:1
<h3><u>Explanation;</u></h3>
What is the concentration of H+ ions at a pH = 7?
The formula for ph is given by:
pH=−log10[H+]
In calculating for the concentration of hydrogen ion, the formula is given by:
[H+]=(10)^(-pH)
Therefore; at pH = 7
[H+]=(10)^(-7)
<u>= 0.0000001 mol/L </u>
What is the concentration of OH– ions at a pH = 7?
pH+pOH=14
7+pOH=14
pOH= 7
[OH-]=(10)^(-pOH)
[OH-]=(10)^(-7)
<u>= 0.0000001 mol/L </u>
What is the ratio of H+ ions to OH– ions at a pH = 7?
1:1
B. they had different beliefs and backgrounds.