Its on Google..."The group number of a representative element in the periodic table is related to the number of valence electrons it has. ... Elements of the halogen family lose one electron to become halide ions."
If more reactant is added, the equation will shift to the right in order to make more product (which will increase the products)
The answer is D. Use the equation PV=nRT
P=(.567mol)(.0821)(300K)/4.5L