Oooooo there's a spongy bone? that's cool! Lol okay okay, I will research it and help you out.
Here's what I found:
Cancellous bone<span>, also known as </span>spongy<span> or </span>trabecular bone<span>, is one of the </span>two<span> types of </span>bone<span> tissue found in the human body. ... It is very porous and contains red </span>bone<span>marrow, where blood cells are made.</span>
False as oxygen is the second most abundant and nitrogen is the most abundant at 78%.
I think the question meant to say net force on the box. Since force is a vector, the direction matters. 20N left is negated completely by the 50N right, which means the net force is 50N-20N to the right, 30N.
I believe the answer is F. This is because, F stands for Fluorine, which is an element and consists of one atom. A molecule consists of TWO OR MORE atoms held together by chemical bonds. F consists of only one atom, which is Fluorine. So the answer is C. Hope helped.