1) we can calculate the molecular weight of H₃PO₄
atomic mass (H)=1 amu
atomic mass (P)=31 amu
atomic mass (O)=16 amu
molecular weight (H₃PO₄)=3(1)+31+4(16)=98 amu.
1 mol (H₃PO₄)=98 g
1 mol= 6.022 * 10²³ molecules.
2) we calculate the mass of 4.00*10²³ molecules.
98 g-------------------6.022*10²³ molecules
x------------------------4.00*10²³ molecules
x=(98 g * 4.00*10²³ molecules) / 6.022*10²³ molecules≈65 g
Answer: 65 g
D, 2Cu + O2 → 2CuO. A is wrong because oxygen is a diatomic element, meaning it always has to come in the form of O2 in the case of gas. B is wrong because the equation isn't balanced correctly; there's two oxygens on the reactants side, while only one oxygen on the products side. C is wrong because it's saying you're STARTING OUT with CuO already: that doesn't correspond with the word problem. Thus leaves D, where the equation is balanced correctly, has the diatomic oxygen, and ends with CuO.
Answer:
Numbers of electrons transferred in the electrolytic or voltaic cell is 6 electrons.
Explanation:
The substance having highest positive reduction 
potential will always get reduced and will undergo reduction reaction.
Reduction : cathode
..[1]
Oxidation: anode
..[2]
Oxidation reaction occurs at anode and reduction reaction occurs at cathode.
To calculate the 
of the reaction, we use the equation:
The overall reaction will be:
2 × [1] + 3 × [2] :
Electrons on both sides will get cancelled :
Numbers of electrons transferred in the electrolytic or voltaic cell is 6 electrons.
Answer is: <span>D. Tin atoms give electrons to lead(II) ions and are oxidized to tin(II) ions.
Chemical reaction: Sn</span>⁰ + Pb²⁺ → Sn²⁺ + Pb.
Tin atom (oxidation number 0) give two electrons to led ions, oxidation number of tin is greater now (oxidation number +2).
<span>Oxidation is loss of electrons.</span>
