How do you convert 3.00 x 10^8 meters/second to miles per hour? confused about the 10^8

Once similarity and one difference between a mixture of elements and a mixture of compounds

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

The mass of a proton is approximately equal to the mass of