Answer: Ag: 2.79x10^22 atoms
C atoms: 6.02x10^23 C atoms
Explanation:
5.0 grams of Ag is 0.0464 moles of Ag. (0.0464 moles)*(6.02x10^23 atoms/mole) = 2.79x10^22 atoms Ag
(0.50 moles)*(6.02x10^23 molecules/mole)*(2 C atoms/molecule) = 6.02x10^23 atoms of C
1 mole ----------- 22.4 L ( at STP )
3.75 moles ----- ?
3.75 x 22.4 / 1 => 84.0 L
0.042 moles of Hydrogen evolved
<h3>Further explanation</h3>
Given
I = 1.5 A
t = 1.5 hr = 5400 s
Required
Number of Hydrogen evolved
Solution
Electrolysis of water ⇒ decomposition reaction of water into Oxygen and Hydrogen gas.
Cathode(reduction-negative pole) : 2H₂O(l)+2e⁻ ⇒ H₂(g)+2OH⁻(aq)
Anode(oxidation-positive pole) : 2H₂O(l)⇒O₂(g)+4H⁻(aq)+4e⁻
Total reaction : 2H₂O(l)⇒2H₂(g)+O₂(g)
So at the cathode H₂ gas is produced
Faraday : 1 mole of electrons (e⁻) contains a charge of 96,500 C

Q = i.t
Q = 1.5 x 5400
Q = 8100 C
mol e⁻ = 8100 : 96500 = 0.084
From equation at cathode , mol ratio e⁻ : H₂ = 2 : 1, so mol H₂ = 0.042