Answer:
2.80×10^23atoms
Step-by-step explanation:
1mol of any element contains 6.02×10^23 atoms (Avogadro's constant)
1mole of copper is 64g
64g contain 6.02×10^23 atoms
29.78g will contain X atoms
29.79g × 6.02×10^23atoms= 64g×Xatom
X= 29.79g×6.02×10^23atoms/64g
X=2.80×10^23atoms