The partial pressure of nitrogen is $110 \mathrm{mm},$ of helium is 10 cm and of carbon dioxide is $1.2$ atm. Calculate the total pressure of total gases present in the isolated gaseous vessel. 

$$\begin{gathered} {\mathrm{P}}_{{\mathrm{N}}_2}=110 \mathrm{mm} \\ {\mathrm{P}}_{\mathrm{He}}=100 \mathrm{mm} \\ {\mathrm{P}}_{{\mathrm{CO}}_2}=1.1 \mathrm{atm}\times \frac{760 \mathrm{mm}}{1 \mathrm{atm}}=836 \mathrm{mm} \end{gathered}$$

According to Dalton's Law of partial pressure:

$\mathrm{Total} \mathrm{pressure} \mathrm{of} \mathrm{gas}={\mathrm{P}}_{{\mathrm{CO}}_2}+{\mathrm{P}}_{\mathrm{He}}+{\mathrm{P}}_{{\mathrm{N}}_2}$

Substitute the values:

$\begin{array}{l}\mathrm{Total} \mathrm{pressure} \mathrm{of} \mathrm{gas}=110 \mathrm{mm}+100 \mathrm{mm}+836 \mathrm{mm}\\ =1046 \mathrm{mm}\end{array}$