Answer:- 3.
and 
Explanations:- An empirical formula is the simplest whole number ratio of atoms of each element present in the molecule/compound.
For example, the molecular formula of benzene is
. The ratio of C to H in it is 6:6 that could be simplified to 1:1. So, an empirical formula of benzene is CH.
In the first pair, the ratio of C to H in first molecule is 2:4 that could be simplified to 1:2 and the empirical formula is
. In second molecule the ratio of C to H is 6:6 and it could be simplified to 1:1. and the empirical formula is CH. Empirical formulas are different for both the molecules of first pair and so it is not the right choice.
In second pair, C to H ratio in first molecule is 1:2, so the empirical formula is
. The C to H ratio for second molecule is 1:4, so the empirical formula is
. Here also, the empirical formulas are not same and hence it is also not the right choice.
In third pair, C to H ratio in first molecule is 1:3, so the empirical formula is
. In second molecule the C to H ratio is 2:6 and it is simplified to 1:3. So, the empirical formula for this one is also
. Hence. this is the correct choice.
In fourth pair, first molecule empirical formula is CH. Second molecule has 2:4 that is 1:2 mole ratio of C to H and so its empirical formula is
. As the empirical formulas are different, it is not the right choice.
So, the only and only correct pair is the third one. 3.
and 
If your science teacher says B, it’s probably because water has a negative and positive end, heat is just a form of energy, as other atoms can’t leave (they’re attracted to the ends) they are being insulated; but notice that ice will melt into gas (where atoms have tons of space) for other atoms to escape. Hence ice and gas aren’t ideal. (Air is a gas here.)
It’s not a 100% but hopefully it helps with some kind of analogy.
Answer: Aluminium
Explanation:
The metals are solid substances, they have shiny luster, they conduct electricity and have high melting point. The aluminium is a kind of metal that have a solid surface, it has a shiny luster, the surface of metal appears to be polished. It conducts electricity and can be used in electrical cords, connections, and devices. It has a high melting point.