PLEASE HELP! NEED THIS ANSWER!

If a plot weight (in g) vs. volume (in ml) for a metal gave the equation y= 13.41x and r^2=0.9981 what is the density of the metal?

Which can be observed only in a microscopic view? a) structure of a muscle cell b) shape of a soybean plant c) foam insulation d) x-ray of a knee joint

Asolution of naoh has a concentration of 25.00% by mass. what mass of naoh is present in 0.250 g of this solution? use the periodic table in the toolbar if needed. 0.0625 g what mass of naoh must be added to the solution to increase the concentration to 30.00% by mass? g