D. all of these can produce nuclear energy
Answer:

Explanation:
Empirical formula of ionic compound formed by two ions
and
is
(for
) of AB (for x = y)
The above empirical formula is in accordance with charge neutrality principle
Here each cation (
and
) can form two ionic compounds by combining with two given anions (
and
).
So the four ionic compounds are: 
Electrons is located outside the nucleus
There are several information's already given in the question. Based on those information's, the answer can be easily deduced.
Amount of gasoline required by Harry's car to travel 25 miles = 1 gallon
Then
amount of gasoline required
by Harry's car to travel 15000 miles = 15000/25
= 600 gallons
So
Amount of CO2 released by burning 1 gallon of gasoline = 20 pounds
Then
Amount of CO2 released
by burning 600 gallon of gasoline = 600 * 20
= 12000 pounds
From the above deduction, it can be concluded that the amount of CO2 that will be added by Harry's car to the atmosphere is 12000 pounds.