Answer:
please mark me as brainliest so difficulty to find me and edit
1 is The first one
<span>2 is the third one
3 is the second one
4 is the 4th one</span>
When burning sodium (Na) in oxygen (O2), you get sodium oxide (Na2O) and/or sodium peroxide (Na2O2). At high pressures, you can additionally get sodium superoxide (NaO2).
4 Na + O2 → 2 Na2O, and then partially 2 Na2O + O2 → 2 Na2O2.
Under normal conditions, approximately 20% of the mixture is Na2O2.
6 Na + 2 O2 → 2 Na2O + Na2O2
hope it helps
Water is molecule formed by the covalent bonding of two atoms of hydrogen with one atom of oxygen. The chemical and physical properties of water are different from each of it's constituent elements Oxygen and Hydrogen. The properties of a drop of water will depend on the simplest unit of water, which is the water molecule 
. Therefore, the smallest unit of the water drop that retains all the physical and chemical properties exhibited by a sample of water is the molecule.
Because it represents 2 atoms of carbon not 2 molecules of carbon
