The number of nodal planes in a p_x orbital is

The electrons, identified by quantum numbers n and l, (i) n = 4, l = 1, (ii) n = 4, l = 0, (iii) n = 3, l = 2 and (iv) n = 3, l = 1 can be placed in order of increasing energy, from the lowest to highest, as

The orbital diagram in which the Aufbau principle is violated is

ASSERTION:
Nuclide $${}_{13}^{30}Al$$ is less stable than $${}_{20}^{40}Ca$$

REASON:
Nuclides having odd number of protons and neutrons are generally unstable.