Which has more mass a kilogram of bricks or a kilogram of feathers explain

Which diagram shows the correct way to represent an ionic compound of magnesium oxide?

If you add 5.00 ml of 0.100 m sodium hydroxide to 50.0 ml of acetate buffer that is 0.100 m in both acetic acid and sodium acetate, what is the ph of the resulting solution? acetic acid: ka = 1.8. x 10-5

Classify this reaction: 2al+n2-> aln.