Answer:
4.2 g
Step-by-step explanation:
The VOLUME of the ring is 4.2 - 4.0 = .2 ml = .2 cm^3
the MASS of the ring is this times the density
.2 cm^3 * 21 g/cm^3 = 4.2 g
the answer is c
density is mass/volume
so mass=density × volume
but we take the change is volume that is v2-v2=4.2-4=0.2ml
but the density is in gm/cm^3 so we should convert ml into cm^3. eventually they are equal so mass=21×0.2=4.2
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