How much heat is released when 12.0 grams of helium gas condense at 2.17 K? The latent heat of vaporization of helium is 21 J/g.

Condensing helium releases heat, so the heat change is negative. Using q = −mL, q = −(12.0 g)(21 J/g) = −252 J, which rounds to −250 J. Therefore, the correct choice is A, −250 J.

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