Answer
Yes. Yes.
Work Step by Step
a. The de Broglie wavelength is inversely proportional to the particle’s momentum, $\lambda = \frac{h}{p}$, so if the particle has a small mass and is very slow, the wavelength can be bigger than the dimensions of the particle.
b. A large-mass particle moving quickly will have a large momentum, and it is possible for the de Broglie wavelength to be smaller than the dimensions of the particle
There is no direct connection between a particle’s size and its de Broglie wavelength.
