Why would heating the gas in an air balloon make the ballon rise?

or:Why would heating the gas in an air balloon make the ballon rise?or:Hot Air rises on it's own. So if they heat it int he ballon it makes it rise

or:Why would heating the gas in an air balloon make the ballon rise?

or:Hot Air rises on it's own. So if they heat it int he ballon it makes it rise

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