Which element is the most electronegative and why?

Fluorine. Electronegativity increases from left to right in a row as the outermost electron ring approaches completion. The closer to completion, the more attractive it is to another electron. Once complete (the far right noble gas column), they are stable and no longer attactive to additional electrons. So that gets us to the secondmost column from the right. Electronegativity also increases from bottom to top of a given column because it is inversely related to atomic radius. The closer to the positively charged nucleus the outermost electron ring is, the stronger it is held and the stronger it can grab that last electron it's missing. So all the way to the right (minus the noble gas column) and all the way up brings us to fluorine.

How do I write a great conclusion?

A great conclusion is all about the "so what?" You've just spent your entire paper asserting and defending your compelling and controvertible thesis (right?) and now's your opportunity to show WHY that paper was worth reading. You don't need to restate your argument, hopefully the reader got that by now. Now what matter is what new insights your paper provides about a work being analyzed or what it adds to or alters regarding the current thinking of a subject. In short, what has the reader gained from having read your paper and why is that worthwhile? If your whole paper has been a focused beam of information (AKA your thesis) now is when that beam explodes and fans out and your reader realizes why what you've said matters to your source material, subject, or world.

What do the two numbers in a time signature mean?

The bottom number tells you what kind of note "gets the beat" in a measure (the area between two consecutive vertical bar lines). If you were to tap your foot to the music, the bottom number is the kind of note you would typically tap. The most common bottom number is 4 so a 1/4, or quarter, note would get a beat if you saw a 4 on the bottom. If you see a 2 on the bottom, a 1/2, or half, note is what you would tap your foot to, and an 8 on bottom means you tap your foot in 1/8, or eighth, notes. Once you've got that, the top number just tells you how many of that note, or how many foot taps, happen in a single measure. 3/4 is 3 quarter notes per measure, 7/8 is 7 eighth notes, and so on.