We know that the equation for density is:
[tex] D=\frac{m}{V} [/tex]
where D is the density, m is the mass in grams, and V is the volume.
Given two of the variables, we can then solve for density:
[tex] D=\frac{0.196g}{100mL}= \frac{0.00196g}{mL} [/tex]
So therefore, we now know that the density of carbon dioxide gas is 0.00196g/mL.