Question

1. a cup of milk contains around 0.305 grams of calcium, how many moles is this? (answer in scientific notation)

Explanation:

Step1: Determine the molar mass of calcium

The molar mass of calcium ($Ca$) is $40.08\ g/mol$.

Step2: Use the formula $n=\frac{m}{M}$

Here, $m = 0.305\ g$ (mass of calcium) and $M=40.08\ g/mol$ (molar mass of calcium).
So, $n=\frac{0.305}{40.08}$.
Calculate $\frac{0.305}{40.08}\approx7.61\times10^{-3}$.

Answer:

$7.61\times 10^{-3}$ moles