If you want to make 2 moles of Silver from the reaction below, how many grams of copper should you start with?

Reaction: Cu + 2AgNO3 → 2Ag + Cu(NO3)2

Can someone me with questions 12 and 13 plz.

Which element has the lowest electronegativity? calcium(ca) gallium(ga) selenium(se) bromine(br)

For the reaction shown, find the limiting reactant for each of the following initial amounts of reactants. 4al(s)+3o2(g)→2al2o3(s) a) 1 molal, 1 mol o2 b) 4 molal, 2.6 mol o2 c) 16 molal, 13 mol o2 d) 7.4 molal, 6.5 mol o2