) What is moleculer formula? What information -
does it give ?

The molecular formula expresses information about the proportions of atoms that constitute a particular chemical compound, using a single line of chemical element symbols and numbers. Sometimes it also includes other symbols, such as parentheses, dashes, brackets, and plus (+) and minus (–) signs.

i do not get it   at all

the transfer of heat by electromagnetic radiation is called thermal radiation . it is usually carried out by electromagnetic waves in an energy range just below the visible spectrum, which is the infrared range.

so the answer would be radiation.

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