Need help with chemistry question

What is the empirical formula of c6h18o3? ch3o c2h5o c2h6o c2h5o5

Which element has the lowest electronegativity? calcium(ca) gallium(ga) selenium(se) bromine(br)

Harry lives in a city, and he has a lung condition known as asthma. on certain days, harry has to stay inside because pollutants in the air make it difficult for him to breathe. which of these pollution sources are nonpoint sources that might bother harry if he goes outside? choose the two that apply.