b
(b) According to \(\Delta x\; \times m\; \times \Delta v = \frac{h}{{4\pi }}\); \(\Delta v = \frac{h}{{\Delta x\; \times m\; \times 4\pi }}\) \( = \frac{{6.6 \times {{10}^{ - 34}}}}{{{{10}^{ - 5}} \times 0.25 \times 3.14 \times 4}} = 2.1 \times {10^{ - 29}}\;\;m/s\)