I think the answer is (4) 600.K and 0.50 atm, for gases behave most ideally at high temperature and low pressure.
Hope this helps~
Answer:
2ErF3 +3Mg = 3MgF2 + 2Er
Explanation:
This is a single replacement equation where there are 2 metals. The bonds are broken and new bonds are formed again by Mg and F.
Er has a +3 charge and F has a -1 charge. You switch it around and you get ErF3. Then you add the second reactant, Mg. The product is MgF as stated, and Mg has a charge of +2 and F has -1. You switch it again and you get MgF2. Then the second product Er is there.
Now we have
ErF3+Mg=MgF2+Er
So we balance the equation because of the law of conservation of mass.
Make F equal, so we add the coefficents 2 and 3
2ErF3+Mg=3MgF2+Er
And now Mg and Er need balancing so
2ErF3+3Mg=3MgF2+2Er
Hope this helped
