An element X belongs to IV period and 10th group in the periodic table. Give the valence shell electronic configuration of the element which is diagonal to the element X that belongs to 5th period

The correct option is C $\left[Kr\right]4d^{10}5s^1$
The element X belongs to IV period and tenth group is Ni. The element diagonal to it and of fifth period is Ag and Rh. Their configuration are $\left[Kr\right]4d^{10}5s^1$ and $\left[Kr\right]4d^{8}5s^1$ respectively.