Molar mass :
H₂O = 18.0 g/mol
O₂ = 32.0 g/mol
<span>2 C</span>₄<span>H</span>₁₀<span> + 13 O</span>₂<span> = 8 CO + 10 H</span>₂<span>O
</span>
13 x 32.0 g O₂ ------------- 10 x 18.0 g H₂O
? g O₂ ------------- 2.46 g H₂O
Mass O₂ = 2.46 x 13 x 32.0 / 10 x 18.0
Mass O₂ =1023.36 / 180
=> 5.68 g of O₂
hope this helps!
1 mole Cu ------------------ 6.02x10²³ atoms
0.90 moles Cu ------------ ??
0.90 x ( 6.02x10²³ ) / 1 =
= 5.41x10²³ atoms