Question

what would happen if sodium and potassium are kept in open air ?

Answer 1

it burn vigorously, when it react with open air

Answer 2

hey mate here is ur ans

sodium and potassium are highly reactive elements

when placed in air they burn with oxygen present in air forming sodium oxide and potassium oxide which are highly exothermic reactions too thus there is risk of fire
or with moisture forming respective hydroxides
2Na+O2--->Na2O
2K+O2----->K2O

added info
it is stored under kerosene Which is an organic unreactive liquid

hope it helps you