Question

What is the relative atomic mass and atomic mass of calcium?

• A. $40.0,40\text{u}$
• B. $39.90,40.078\text{u}$
• C. $40.078,40.078\text{u}$
• D. $40.078,41.0\text{u}$

Answer 1

The correct option is C $40.078,40.078\text{u}$

$\text{Relative atomic mass of an element (R.A.M)}=\frac{\text{Mass of one atom of the element}}{\frac{1}{12\text{th}}\times \text{mass of}{C}^{12}\text{atom}}$
Relative atomic mass of $Ca=40.078$
Atomic mass of $Ca=\text{R.A.M}\times 1\text{amu}=40.078\text{amu}$