Answer:
The 3rd one is correct
Explanation:
Protons and neutrons have approximately the same mass, about 1.67 × 10−24 grams, which scientists define as one atomic mass unit (amu) or one Dalton. Each electron has a negative charge (−1) equal to the positive charge of a proton (+1). Neutrons are uncharged particles found within the nucleus.
Krypton. The atomic radius decreases as you go across a period.
2Fe + 3Cl₂ ---> 2FeCl₃
4.4mol of Fe, you have a 2:3 ratio of Fe to Cl₂ so divide 4.4/2 = 2.2 and multiply by three 2.2 x 3 = 6.6mol of Cl₂
hope that helps :)