1. Which of these show a diatomic element? CO
H₂
He
SO₂
2. Which of these substances is an element?
Chlorine
Ice
Methane
Sodium chloride
3. When the elements lead and bromine combine together, the name of the substance formed is called
Lead bromate
Lead bromide
Lead bromite
Lead bromium

Can anyone (a-level) a student was analysing a carbonate compound, mco3, containing an unknown group 2 metal, m. the student carried out thermal decomposition on 0.730g of the carbonate and measured the volume of gas produced. mco3 (s) mo (s) + co2 (g) the student collected and measured 120cm3 of carbon dioxide. 1 mol of carbon dioxide occupies 24 000 cm3 under these conditions. calculate the molar mass of the group 2 carbonate and hence deduce the identity of the group 2 metal, m.

Which of the following observations indicates that there is a small, dense, positively charged part in the center of an atom? some uncharged particles are scattered by a gold foil. all uncharged particles are attracted towards a gold foil. all positively charged particles pass straight through a gold foil. some positively charged particles bounce back from a gold foil.

Can someone me with 3 and 4 plz. this is for masteries test.