the density of alcohol is 0.79g/ml. find the mass of 15.5ml of alcohol?
15.5ml x 0.79g/ml = mass 12.245g
That looks ok to me BUT you have too many significant figures. If the 0.79 is density you are allowed only two so you should round the answer to 12. If the density is given as 0.790 you can have three and round to 12.2.
To find the mass of 15.5 ml of alcohol, you can use the formula:
Mass = Volume x Density
In this case, the volume is given as 15.5 ml and the density of alcohol is given as 0.79 g/ml. By substituting these values into the formula, you get:
Mass = 15.5 ml x 0.79 g/ml
Calculating this gives you a mass of approximately 12.245 g.