When the pressure that a gas exerts on a sealed container changes from 3.74 atm to atm, the temperature changes from 394 k to 789 k

Gay-Lussacs law gives the relationship between pressure and temperature of a gas.
It states that pressure of gas is directly proportional to the temperature at constant volume.
P/T = k
Where k - constant
P1/T1 = P2/T2
Where parameters for the first instance are on the left side and parameters for the second instance on the right side of the equation.
3.74 atm /394 K = P/789 K
P = 7.49 atm

Burned piece of steel wool does not gain mass. so only d could be true.

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