Super alloys are usually

Iron $(Fe)$ is classified as:

State whether the following statements are true or false:
$(i)$ Atomic size increases with an increase in the atomic number of elements.
$(ii)$ The electron gain enthalpy for noble gases is approximately zero.
$(iii)$ The first element of the actinoid series is $Th$ and the last element is $Lu$.
$(iv)$ The general electronic configuration of $d$-orbitals is always $(n-1)d^{1-10}ns^2$.

Which transition element does not exhibit variable oxidation states?

Which of the following is a correct statement?

In the electronic configuration of which of the given elements,$Aufbau$ principle or $(n+l)$ rule is violated?