Yes. In a homogeneous mixture the hydrogen and oxygen are not chemically combined; in water vapor, they are. You can separate a homogeneous mixture of hydrogen and oxygen by physical means, such as by cooling the mixture until the oxygen liquefies. If you cool water vapor you're just going to get liquid water and then ice - not two separate substances. That's because compounds can only be separated into their elements by chemical means.
Volume of 1 mol of gas at standard temperature and pressure is 22.4 L.
That is using ideal gas equation:
PV = nRT
P=pressure
V=volume
n=number of moles
R=gas constant
T=temperature
at STP,
P=1 atm
T=273K
n=1(given)
Putting all the values in the equation will give,
V= 22.4 L
So, the answer is :
The volume of 1 mol of gas at standard temperature and pressure is 22.4 L.
Answer: Out of the given options 
is expected to have the highest viscosity.
Explanation:
The resistance occurred in the flow of a liquid substance is called viscosity.
More stronger is the intermolecular forces present in a substance more will be its resistance in its flow. Hence, more will be its viscosity.
For example, has strong intermolecular hydrogen bonding than the one's present in 
and 
. This is because two-OH groups are present over here.
Thus, we can conclude that out of the given options is expected to have the highest viscosity.
