In the reaction na2co3 + 2hcl → 2nacl + co2 + h2o, how many grams of co2 are produced when 7.5 moles of hcl is fully reacted?

Since the above equation is balance we move directly to the problem,
2 moles of hcl produce 1 mole of co2
7.5 produces x
use ratio method we get: 3.75moles of co2 are produced
1 mole of co2 = 44.01g
3.75 moles = x
x= 165.03g of co2

Most smaller stars don't have a radiative zone.