solution:
The quoted atomic mass on the Periodic Table is the WEIGHTED average of the individual isotopic masses. The higher the isotopic percentage, the MORE that isotope will contribute to the isotopic mass. For this reason, most masses that are quoted on the Table are non-integral.
By way of example we could look to the hydrogen atom. The VAST majority of hydrogen atoms (in this universe) are the protium isotope. i.e. 1H, whose nuclei contain JUST the defining proton. There is a smaller percentage (>1%) of hydrogen atoms WITH one NEUTRON in their nuclei to give the deuterium isotope. i.e. 2H, and because this is relatively cheap, and easily incorporated into a molecule, deuterium labelling is routinely used in analysis.
And there is even a smaller percentage of hydrogen atoms with TWO NEUTRONS in their nuclei, to give the tritium isotope. i.e. 3H. The weighted average of the isotopic percentages gives 
Molar mass:
KCl = 74.55 g/mol
KClO3 = 122. 55 g/mol
<span>Calculation of the mass of KClO3 :</span>
<span>2 KClO3 = 2 KCl + 3 O2</span>
2* 122.55 g KClO3 ------------------ 2 * 74.55 g KCl
mass KClO3 ?? --------------------- 25.6 g KCl
mass KClO3 = 25.6 * 2 * 122.55 / 2 * 74.55
mass KClO3 = 6274.56 / 149.1
mass = 42.082 g of KClO3
Therefore:
1 mole KClO3 ---------------------- 122.55 g
?? moles KClO3 ------------------- 42.082 g
moles KClO3 = 42.082 * 1 / 122.55
moles KClO3 = 42.082 / 122.55
=> 0.343 moles of KClO3
Answer C
hope this helps!
When looking down the groups the elements have an equal number of electrons in the outer shell. This means they react in a similar way making it easier for scientists to use.
Given the molar mass of Nitrogen is 14.01g/mol you can use that to solve for the moles of nitrogen.
0.235g(1mol/14.01g) = .0168 moles.
The variable that is measured as data in an experiment is 1. the dependent variable.
The variables that are held constant in an experiment are 2. the controlled variables.
The variable that is changed by the experimenter is 5. the independent variable.
A count or measurement recorded during an experiment is 4. quantitative data.
Descriptions or observations during an experiment are 3. qualitative data.
