Calculate the mass of carbon dioxide in which there are as many molecules as there are molecules in 4.5 g of water.

Find the number of mol of water n (H2O) = m / M = 4.5 / 18 = 0.25 mol
The number of molecules can be found by the formula N = n * Na
Because the number of molecules is the same (Na = number of avogadro 6 * 10 ^ 23) then the number of moles is the same. n (CO2) = 0.25 mol
Find the mass
m (CO2) = n * M = 0.25 * 44 = 11g