Answer:
d ≈ 0.098 g/mL
Step-by-step explanation:
The density of a substance can be found by dividing the mass by the volume. 
d=m/v
The mass of the substance is 0.221 grams and the volume is 2.25 milliliters. 
m= 0.221 g 
v= 2.25 mL 
Substitute the values into the formula. 
d= 0.221 g / 2.25 mL 
Divide 
d= 0.098222222 g/mL
Let’s round to the nearest thousandth. The 2 in the ten thousandths tells us to keep the 8 in the thousandth place. 
d ≈ 0.098 g/mL 
The density of the substance is about 0.098 grams per milliliter.