The first step Niven has to do
in his calculation is to Balanced the chemical equation. The answer is letter
A. The key in the balancing of chemical reaction is to make sure that you got
the exact chemical formula of the substance that is reacting and the yielded
product. After getting the formula, identify first the hardest element/atom to
be balanced such as Na, Zn, Cl, etc. Then proceed to the easier ones such as O,
H. Make sure to not the atoms present in the molecule of the substance.
<span>Molarity is expressed as the number of moles of solute per volume
of the solution while molality is expressed as the number of moles solute per
mass of solution. We calculate as follows:</span>
5.74 mol / kg (1.238 kg/L) = 7.10612 mol / L or 7.11 M
"High temperatures make the gas molecules move more quickly" is the one sentence among all the choices given in the question that most likely explains why this reaction is carried out at high temperature. The correct option among all the options that are given in the question is the third option or option "C".
Answer: D) 1.00 g
Explanation:
According to the Avogadro's law, the volume of gas is directly proportional to the number of moles of gas at same pressure and temperature. That means,

or,

where,
= initial volume of gas = 2.00 L
= final volume of gas = 3.00 L
= initial moles of gas =
= final moles of gas = ?
Now we put all the given values in this formula, we get


Mass of helium =
Thus mass of helium added = (3.00-2.00) g = 1.00 g