Do metals lose or gain electrons

Combustion is the act or process of burning. therefore, i believe the answer is  a: burning wood. 

The main types of electromagnetic radiation. radio  waves have  the lowest frequencies  and  longest  wavelengths, while gamma  waves have highest frequencies  and shortest wavelengths. the wavelengths vary across the electromagnetic spectrum from about 10–15 m to more than 104 m.hope it !

The answer is  a: x-rays—2 and ultraviolet rays—3.  hope i !