We are not here to answer HW questions for you, but to help. Please show attempts.
However, since I feel like I should correct some things kylon said, you are in luck.
A) The alkali metals chemical role is not to produce hydrogen. The alkali metals readily form the +1 cations.
This means their typical role in chemical reactions is to provide an electron. To be more chemically literate about it, their role is to be oxidized or in other words act as a reducing agent. In general simplified terms.
Example with sodium:
Na -> Na+ + e-
B) Kylon is correct that they need 7 more electrons to fill up their valence orbitals. But it is so highly energetically unfavorable to add 7 electrons to the alkali metals, it is reasonable to say it is impossibles.
However, as mentioned earlier, they readily lose and electron forming the +1 cations. This gives them filled valence electron shell of the noble gas preceding them on the periodic chart.
Halogens have 7 valence electrons and need only 1 electron, which can easily be donated by an alkali metals. Which is why they play together so nicely (ok, a very simplified reason to justify their reactivity with each other).
C) Are reasonable chemical reactions. Include the phases though (solid, liquid, gas, aqueous).