Water is a compound. A compound is made up of two or more elements. In the case of water, or H2O, there are 2 hydrogen atoms present and 1 oxygen atom. I hope this helps you on your assignment. Good luck!
Well the substance amount would be 45 because it will rise and began to drop temp while still being heated debate over the eastern half of the Roman empire became known as the teacher apologise for the teacher apologise to do ariana grande
Mezoic era began 252m years ago and ended 6.6m years ago.
It was a time of geological and biological transition. During this era the continents began to drift to their present configuration.
3 of the largest mass extinction occurred at this era. One which include the dinosaurs.
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Explanation:
It is known that rate of effusion of gases are inversely proportional to the square root of their molar masses.
And, half of the helium (1.5 L) effused in 24 hour. So, the rate of effusion of He gas is calculated as follows.
= 0.0625 L/hr
As, molar mass of He is 4 g/mol and molar mass of
is 32 g/ mol.
Now,

= 2.83
or, rate of
= 
Rate of
= 0.022 L/hr.
This means that 0.022 L of
gas effuses in 1 hr
So, time taken for the effusion of 1.5 L of
gas is calculated as follows.
= 68.18 hour
Thus, we can conclude that 68.18 hours will it take for half of the oxygen to effuse through the membrane.