PX154 - D4a - isobars

constant pressure
then, from here:

W = p (V_{1} - V_{2})

also, from here:

p V = n R T

$p :$ constant, $V :$ increases $⟹ T$ increases $⟹ Δ U$ increases
$Δ U = Q - W ⟹ Q$ must be large