19) Density of water is 1g/ml !!
* It is important because we use it in solving problems and day to day life !!
20) a)
Density = mass/volume
= 300g/100ml
= 3g/ml
b) Change in volume = 5ml
density= 50g/5ml
= 10g/ml
c)Mass = density× volume
= 1g/ml × 400ml
= 400g
21) as density is low it will float !!
vol inside / vol outside = Density of solid/ density of liquid ;
= .75/1
= 3/4
so just make a box with 3/4 part inside and 1/4 part ouside of water :)
if you got any problem in understanding let me know !!