Can u plazas help me with this fast

Acycloalkane molecule contains 8 carbon atoms. how many hydrogen atoms are present in the molecule?

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

A650 ml sodium bromine solution has a bromide ion concentration of 0.245 m. what is the mass (g) of sodium bromide in solution? a) 103.b)0.00155.c)16400.d) 16.4.e) 0.159