Fluorine and lithium react together to form lithium compound that contains F^- and Li^+ ions. What is the formula of the compound formed?

What else but $L i F$?
Positive and negative ions can combine to form NEUTRAL salts. Neutrality demands a 1:1 formula for $L {i}^{+}$ and ${F}^{-}$. Common salt, $N a C l$, is another example.
What salt would be formed by $L {i}^{+}$ and $S {O}_{4}^{2 -} \text{(sulfate ions)}$?