Density of ice/water, conductivity, and fuel calculations

15. The density of liquid water at 0 degrees C is 0.9987 g/cm cubed; the density of ice at this same temperature is 0.917 g/cm cubed.

a. Calculate the volume occupied at 0 degrees C by 100. g of liquid water and by 100. g of ice.
b. Calculate the percentage increase in volume when 100. g of water freezes at 0 degrees C.

19. Predict what will happen when each of these dilute solutions is tested for conductivity. Please explain to me why you made your predictions.

a. CaCI2 (aq)
b. C2H5OH (aq)
c. H2SO4 (aq)

23 b. A coal-burning power plant generates electrical power at a rate of 500 megawatts; that is, 500 X 10 to the 6th power pr 5.00 X 10 to the 8th power joules per second. The plant has an overall efficiency of 0.375 for the conversion of heat to electricity. Assuming the power plant burns coal that releases 30 kJ/g, calculate the mass of coal (in grams and metric tons) that will be burned in 1 year of operation (1 metric ton = 1 X 10 to the 3rd power kg = 1 X 10 to the 6th power g).

The answer is 1.40 X 10 to the 12th power g; 1.40 X 10 to the 6th power metric tons but please show me how to do the calculations so I will have a future reference.