1.25 X 10^24 molecules of chlorine gas react with sodium to form how many grams of sodium chloride?
2Na + Cl2
--> 2NaCl

241.28 g NaCl(s)

Explanation:

Given 1.25 x 10²⁴ molecules of Cl₂ = 1.25 x 10²⁴molecules Cl₂(g)/6.023 x 10²³ molecules/mole = 2.08 mole Cl₂(g)

2Na(s)    +      Cl₂(g)      =>   2NaCl(s)

excess        2.08mole          ? mole

∴moles NaCl(s) formed from 2.08 moles Cl₂(g) = 2(2.08 mole NaCl(s))

= 4.16 mole NaCl(g) = 4.16 mole NaCl(s) x 58 g NaCl(s)/mole NaCl(s) = 241.28 g NaCl(s)  

c is the answer because when something is left after something evaporates that shows the chemical change.