Answer:
Periods have consecutive atomic number as they are in a row and groups are vertical meaning they are in a column and groups have similar properties
N = 3.2 moles, T = 50 + 273 = 323 K, P = 101.325 kPa, R = 8.314 L.kPa/K.mol
PV = nRT
V = nRT / P substituting.
V = (3.2 mole)(8.314 L.kPa/K.mol )(323 K) / (<span>101.325 kPa)
That is the answer, but it is not among the options you provided. Check your options properly.</span>
Let's eliminate these one by one.
The first pair would not be the same, as X would most likely be in group IA, and Y would be in group VIIA, because of their tendency to gain and lose electrons.
The second pair would also violate the same rule, but X would most likely be in group IIA, and Y would most likely be in group VIA.
The third pair would not be the same, as X is most likely in group VIIA, and since Y has eight valence electrons, it is most likely a noble gas.
The final pair has X with atomic number 15, making it phosphorous. Phosphorous wants to gain 3 electrons to have a full octet of 8 outer "valence" electrons, and Y would also like to gain 3 electrons. This means it is possible that the final pair would be in the same group.
Molarity = Moles of solute/ L(liters) of solution
So let's plug in the information.
5.0 moles/10L = 0.5 M