Question

the mass of a solid substance is 21.1164 g. if the volume of the solid substance is 19.9 cm³, calculate the density of the substance with the correct number of significant digits.
a 1.06 g/cm³
b 420.2 g/cm³
c 11.3 g/cm³
d 115 g/cm³

Explanation:

Step1: Recall density formula

The formula for density $
ho$ is $
ho=\frac{m}{V}$, where $m$ is mass and $V$ is volume.

Step2: Substitute values

Given $m = 21.1164\ g$ and $V=19.9\ cm^{3}$, then $
ho=\frac{21.1164}{19.9}\ g/cm^{3}$.

Step3: Calculate density

$
ho=\frac{21.1164}{19.9}\approx1.061126\ g/cm^{3}$.

Step4: Apply significant - digit rules

The mass has 5 significant digits and the volume has 3 significant digits. When dividing, the result should be reported with 3 significant digits. Rounding 1.061126 to 3 significant digits gives 1.06 $g/cm^{3}$.

Answer:

A. $1.06\ g/cm^{3}$