Answer:
The correct answer is B.
Explanation:
The molecule of water has 2 atoms of hydrogen and 1 atom of oxygen.
The ratio of masses are given as:

This illustrates the law of definite proportions which is also known as law of constant compositions .
The law states that 'the elements combining to form compound always combine in a fixed ratio by their mass.'
Whereas :
Law of multiple proportion states that when two elements combine with each other to form more than one compounds , the mass of one element with respect to the fixed mass of another element are in ratio of small whole numbers.
Law of conservation of mass states that mass can neither be created nor be destroyed but it can only be transformed from one form to another form.
In a balanced chemical reaction ,total mass on the reactant side must be equal to the total mass on the product side.
Law of conservation of energy states that energy can neither be created nor be destroyed but it can only be transformed from one form to another form.
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For the conversions
I will start with pressure
1atm=101.3kPa
x =700kPa
x=700kPa/101.3kPa
x=6.91atm
Temperature
273K+30.00C
303K
Volume
1L=1000ml
x =50ml
x=0.05L
PV=nRT
6.91*0.05=n*0.08206*303
0.3455=24.86418n
0.3455/24.86418=n
0.0138=n
number of moles = 0.0138moles
Note: 0.08206 is the gas constant in this case
Answer:
16 g/mol
Explanation:
In CO2, it means we have 1 mole of carbon and 2 moles of oxygen.
However, we want to find the molar mass of just a single mole of oxygen.
Now, from tables of values of elements in electronic configuration, the molar mass of oxygen is usually approximately 16 g/mol.
In essence the molar mass is simply the atomic mass in g/mol