Verified answer

Figure out the number of moles of acetylene present using the ideal gas law :

Ideal gas law :

PV = nRT

P = (805 mm Hg) x (1 atm / 760 mm Hg) = 1.06 atm

V = 23.8 L

n = ?

R = (0.08206 L•atm / mol•K)

T = 308 K ................... [ converting Celsius to Kelvin; (35.0 + 273) = 308 ]

Rearranging the ideal gas law equation to solve for n gives

n = (PV / RT)

= { [(1.06 atm) x (23.8 L)] / [(0.08206 L•atm / mol•K) x (308 K)]}

= 0.998 moles acetylene

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That's very nearly 1 mole of acetylene,

hence at STP it would have a volume of 22.4 L .

The calculation shows it, of course :

(0.998 moles) x (22.4 L / 1 mole) = 22.4 L .... [ rounded to 3 significant figures ]