Hi sorry
I don’t know
but maybe next time
Answer:

Explanation:
Hello there!
In this case, since the mass percentages in a compound which is wanted to know the molecular formula, can be assumed to be the masses, we first need to compute the moles they have in the formula unit:

Next, we divide each moles by the fewest ones (3.73 mol) in order to find the subscript in the empirical formula first:

Then, the empirical formula is BH2N whose molar mass is 26.83 g/mol, so the ratio of molecular to empirical is 80.50/26.83=3; therefore, the molecular formula is three times the empirical one:

Best regards!
Explanation:
Not only did outermost electron determine the valence electron, but also <em>periodic</em><em> </em><em>table</em><em>.</em><em> </em>whatever group they fall into in periodic table each valence electrons present in a particular atom e.g K and Ca belong to group 1 and 2 respectively and k has 1 and Ca have 2 in each outermost electron
12, if the decimal is over five, round up. If it's not, round down. Not sure what you mean by significant figures.