Answer
a. Decrease.
b. Increase.
Work Step by Step
a. The uncertainty in the particle position is proportional to the width of the probability distribution function.
If the value of $\alpha$ is increased, the wavefunction becomes narrower. The particle’s uncertainty in position decreases.
b. We apply the Heisenberg uncertainty principle for position and momentum.
$$\Delta x \Delta p_x \geq \frac{\hbar}{2}$$
Because the uncertainty in position decreases, the uncertainty in momentum increases.
