Which contains the most moles: 10 g of hydrogen gas, 100 g of carbon, or 50 g of lead?

Carbon

Explanation:

We know that

Number of moles = mass/molecular mass

So

Hydrogen: given as H2 with 10g an atomic number of 1 so MW( 1x 2= 2)

Number of moles = Weight/MW

= 10/2

= 5

Carbon: atomic number 12 C and mass 100

Number of moles = Weight/MW

= 100/12

= 8.33

Lead: atomic num 207 and mW 207 pb

Number of moles = Weight/MW

= 50/207

= 0.241

Therefore Carbon has the most moles.

12000j is work done