The reaction between Na and Cl2 is
2Na + Cl2 ---> 2NaCl
So two moles of Na will react with one mole of Cl2
However here in the given question the moles of Cl2 is constant as mass is constant. Say we have 71 of Cl2 in each container, the moles = 71 / 35.5 = 2 moles of Cl2
Moles of Na = Mass / atomic mass
The container will have following moles of Na
1 ) Moles = 10 / 23 = 0.435 (these will react with 0.2175 moles of Cl2 to give 0.435 moles of NaCl]
2) moles = 20 / 23 = 0.87 ( (these will react with 0.435 moles of Cl2 to give 0.87 moles of NaCl]
3) moles = 30 / 23 = 1.3 ( (these will react with 0.65 moles of Cl2 to give 1.3 moles of NaCl]
4) moles = 40 / 23 = 1.74 (these will react with 0.87 moles of Cl2 to give 1.7 moles of NaCl]
5) moles = 50 / 23 = 2.18 (these will react with 1.09 moles of Cl2 to give 2.18 moles of NaCl]
6) moles = 60 / 23 = 2.61 (these will react with 1.3 moles of Cl2 to give 2.61 moles of NaCl]
7) moles = 70 / 23 = 3 moles (these will react with 1.5 moles of Cl2 to give 3 moles of NaCl]