When 25.0 g of ch4 reacts completely with excess chlorine yielding 45.0 g of ch3cl, what is the percentage yield, according to ch4(g) + cl2(g) → ch3cl(g) + hcl(g)?

Percentage yield = (actual yield / theoretical yield) x 100%

The balanced equation for the reaction is,
    CH₄(g) + Cl₂(g) → CH₃Cl(g) + HCl(g)

Since there is excess of Cl₂ gas, we can assume that all of CH₄ gas are reacted.

Moles of CH₄(g) = mass / molar mass
                           = 25.0 g / 16 g/mol
                           = 1.5625 mol

The stoichiometric ratio between CH₄(g) and CH₃Cl(g) is 1 : 1

Hence moles of CH₃Cl(g) = 1.5625 mol

Molar mass of CH₃Cl(g) = 50.5 g/mol
 
Mass of CH₃Cl(g) = number of moles x molar mass
                             = 1.5625 mol x 50.5 g/mol
                             = 78.9 g
Hence theoretical yield = 78.9 g
Actual yield = 45.0 g

Hence,
 Percentage yield = (45.0 g / 78.9 g) x 100% 
                             = 57.03%

a is the answer to this question

explanation:

conduction is the transfer of thermal energy (heat in transfer) due to collisions between the molecules in the object. collisions between adjacent atoms and molecules transfer kinetic energy from the warmer to the cooler object. the objects must be in physical contact.