Thank you for reporting, we will resolve it shortly
Q.
A sample of copper sulphate pentahydrate, $CuSO_4.5H_2O$ contains 3.782 g of Cu. How many grams of oxygen are in this sample ?
Some Basic Concepts of Chemistry
Solution:
$CuSO_{4}\cdot5H_{2}O$ has $1$ mole of copper and $9$ moles of oxygen atoms
$63.5\,g\, Cu \equiv 9 \times 16\,g$ of oxygen
$3.782\,g\,Cu \equiv \frac{9\times16\times3.782}{63.5}$
$=8.576$ of oxygen