A substance has a volume of 20 ml and a density of 2.5 g/ml. What is it mass? A:0.125g ,B:8g, c:22.5g or D:50g

D. 50g

volume : 20ml

= 0.02 l

density : 2.5g/ml

= 2500 g/l

therefore, p=m/v

m= p x v

= 2500 x 0.02

= 50

the statements that apply here about binary star system are

"have stars that might appear to wobble"

"often have one star that is brighter than other"

a binary star is a star system consisting of two stars revolving around their common barycenter. systems of two or more stars are called multiple star systems.