Answer
$\lambda_1 \gt \lambda_2$
Work Step by Step
We can write an expression for the speed of an electron:
$K = \frac{1}{2}mv^2$
$v= \sqrt{\frac{2~K}{m}}$
Since $K_2 \gt K_1$, then $v_2 \gt v_1$
We can write an expression for the de Broglie wavelength:
$\lambda = \frac{h}{mv}$
Since $v_1 \lt v_2$, then $\lambda_1 \gt \lambda_2$
