Pls tell me which answer type it

In which of the following belong to a category called the main group of elements? nonmetals. transition elements. halogens. alkali metals. it can be more than one answer!

Zoe is investigating the composition of substance a, an unknown substance. using chemical processes, she analyzes substance a and determines it is composed of sodium, oxygen, and hydrogen atoms in a ratio of 1 : 1 : 1. what is substance a? a. a compound b. an element c. a heterogeneous mixture d. a homogeneous mixture

What mass of natural gas (ch4) must you burn to emit 276 kj of heat?