Radon is a radioactive noble gas that can sometimes be found in unventilated basements

Radon is a radioactive noble gas that can sometimes be found in unventilated basements. A sample of 1.35×10−4mol of radon gas is held in a container with a volume of 3.03mL. A quantity of radon gas is added to the container, which is then found to have a volume of 7.79mL at the same temperature and pressure. How many moles of radon were added to the container?

• Report your answer using three significant figures.
• When reporting your answer using scientific notation, use the multiplication symbol, ×, not the letter x.