Answer:
The expression to calculate the mass of the reactant is 
Explanation:
<em>The amount of heat released is equal to the amount of heat released per gram of reactant times the mass of the reactant.</em> To keep to coherence between units we need to transform 1,080 J to kJ. We do so with proportions:

Then,

Answer:
7 orbitals
Explanation:
An f sublevel has 7 orbitals
<u>Given:</u>
Mass = 68 kg
Power = 65 W
<u>To determine:</u>
Calories burned during an 8.0 hr sleep
<u>Explanation:</u>
Energy is expressed as:
Energy = Power * Time
Now, the unit of power = Watt (W)
1 W = 1 J/s i.e. 65 W = 65 J/s
Time = 8 hrs = 8 * 3600 s = 28800 s
Energy = 65 J/s * 28800 s = 1872000 J
Convert Joules (J) to calories (cal)
1 cal = 4.184 J
The calculated energy = 187200 J * 1 cal/4.184 = 447418 cal
Ans: The man burns nearly 447.4 kcal during an 8 hr sleep