Which of the following compounds has a formula unit mass of 100 u?

The correct option is CaCO₃.

Step-by-step Explanation:

The formula unit mass of a compound is calculated by adding together the atomic masses of all the atoms present in its chemical formula.

Let us find the standard atomic masses of the constituent elements:

• Atomic mass of Calcium (Ca) = 40 u

• Atomic mass of Carbon (C) = 12 u

• Atomic mass of Oxygen (O) = 16 u

Now, let us compute the formula unit mass of Calcium Carbonate (CaCO₃):

$\text{Formula unit mass of CaCO}{3}_{}=\text{Atomic mass of Ca}+\text{Atomic mass of C}+3\times \left(\text{Atomic mass of O}\right)$

$=40\text{u}+12\text{u}+3\times 16\text{u}$

$=40\text{u}+12\text{u}+48\text{u}$

$=100\text{u}$

Thus, Calcium Carbonate (CaCO₃) has a formula unit mass of 100 u.