Answer : The mole fraction of NaCl in a mixture is, 0.360
Explanation : Given,
Moles of
= 7.21 mole
Moles of
= 9.37 mole
Moles of
= 3.42 mole
Now we have to calculate the mole fraction of
.

Now put all the given values in this formula, we get:

Therefore, the mole fraction of NaCl in a mixture is, 0.360
Answer : The molecule
is a polar molecule.
Explanation :
Polar molecule : When the arrangement of the molecule is asymmetrical then the molecule is polar.
Non-polar molecule : When the arrangement of the molecule is symmetrical then the molecule is non-polar.
The given molecule is, 
The electronegativities of oxygen and fluorine are different. The molecular geometry of
is bent. As, Fluorine is more elctronegative than the oxygen. So, the arrows putting towards the more electronegative element i.e, fluorine. These arrows do not balance each other. Due to this, the asymmetrical arrangement of these bonds makes the molecule polar.
Hence, the given molecule
is polar.
<span>that it is cooler than the lithosphere.</span>
Like if you imagine making something you create a hypothesis about was to make that happen