<span> strictly speaking, a molecule has at least two atoms. ... Atoms with full valence electron shells are stable. Full Text[ edit ] The noble gases are a group of chemical elements that make up Group 18 on the periodic table.</span>
<span>M<span><span>g<span>(s)</span></span>+</span>2HC<span>l<span>(aq)</span></span>→MgC<span>l<span>2<span>(aq)</span></span></span>+<span>H<span>2<span>(g)</span></span></span></span>
Explanation:
The reaction between magnesium and hydrochloric
acid combine to form a salt of magnesium chloride and release hydrogen
gas. This single replacement reaction is a classic example of a metal
reacting in an acid to release hydrogen gas.
H2SO4(aq)+NaOH(s)----->NA2SO4 + H20
The idea behind a tree diagram is to start on the left with the whole thing, or one. Every time several possible outcomes exist the probability in that branch splits off into a smaller branch for each outcome.
<u>Answer:</u>
(a): The balloon will contain 
number of molecules now.
(b): The gas law associated with this is Avogadro's law.
<u>Explanation:</u>
Avogadro's law states that the volume of the gas is directly proportional to the number of moles of the gas at constant pressure and temperature
Mathematically,
(At constant pressure and temperature)
OR
.....(1)
where,
= Initial volume and number of moles
= Final volume and number of moles
We are given:
Putting values in equation 1, we get:
(a):
If 
number of moles of gas contains X number of molecules
So, 
number of moles of gas will contain = 
number of molecules
Hence, the balloon will contain number of molecules now.
(b): The law used is Avogadro's law.
