Answer : The correct option is, (B) 
Solution :
According to the Graham's law, the rate of effusion of gas is inversely proportional to the square root of the molar mass of gas.

or,
..........(1)
where,
= rate of effusion of unknown gas = 
= rate of effusion of oxygen gas = 
= molar mass of unknown gas = ?
= molar mass of oxygen gas = 32 g/mole
Now put all the given values in the above formula 1, we get:


The unknown gas could be carbon dioxide
that has approximately 44 g/mole of molar mass.
Thus, the unknown gas could be carbon dioxide 
The answer is heart
good luck!
Explanation:
Molarity = mol/L or g/L
Data:
Mass>80.0g
Mr of CaCl2>111.1g/mol
V>500mL
Convert mL to Litres;. mole=g/Mr
1L=1000mL. =80g/111.1g/mol
x=500mL. =0.720072007mol
x=0.5L
Molarity= mole/volume
=0.720072007mol/0.5L
=1.440144014mol/L
=1.4401mol/L
Hope this helps. Depending on the question you can also find it in g/L but mol/L is safer.
Glucose is C6H12O6 and the energy is located in its C-H bonds