A balloon contains 8.4 L of helium gas at STP. How many moles of helium are in the balloon? 0.38 moles He ,190 moles He ,2.1 moles He ,8.4 moles He

Answer 1

At STP (standard temperature and pressure), 1 mole of any ideal gas occupies 22.4 L (it's a good idea to memorize this value)

8.4 L He x 1 mol / 22. 4 L = 0.38 moles He