I'll take a stab at this, but wait for someone more qualified to check my reasoning.
Which elements are likely to be metals?
We're going to want high melting and boiling points here, so F and G look good to me.
Which are gases at STP?
22.4 L is the definition of one mole of at gas at STP, so A nd B look good. The low melting and boiling points confirm this.
Which are most likely to be non-metallic solid?
I would think D and E would be good answers here, because I would say they look like organic compounds from there melting and boiling points.
Which elements are liquid at 200 C?
The melting point will need to be below 200C and boiling point will need to be over 200C, so D and E look good.
Which elements are likely to conduct well in the solid form?
I wouldn't think A and B would be strong electrolytes because they are gases at STP and have characteristics of non-metals. F and G would probably conduct well, because they have the properties of metals and should have the "sea of electrons" needed to allow electrical conductivity.
Once again, please wait for someone to confirm this reasoning.