What is the ground state electron configuration of an atom of chromium, Cr (Z = 24)?

A. [Ar]3d⁶

B. [Ar]4s²3d⁴

C. [Ar]4s¹3d⁵

D. [Ar]4s²4p⁴

C

Some candidates had ground state configuration of Cr as 4s² 3d⁴ rather than 4s¹ 3d⁵

Which representation would be correct for a species, Z, which has 31 protons, 40 neutrons and 28 electrons?

A. ${}_{31}^{71}{\mathrm{Z}}^{3+}$

B. ${}_{31}^{71}{\mathrm{Z}}^{3-}$

C. ${}_{40}^{71}{\mathrm{Z}}^{3+}$

D.  ${}_{28}^{71}{\mathrm{Z}}^{3+}$

A

Which species has two more neutrons than electrons?

${}_3{}^{6}L{i}^{+}$             ${}_4{}^{9}B{e}^{2+}$             ${}_{11}{}^{23}N{a}^{+}$             ${}_{20}{}^{42}C{a}^{2+}$

A.  ${}_3{}^{6}L{i}^{+}$

B.  ${}_4{}^{9}B{e}^{2+}$

C.  ${}_{11}{}^{23}N{a}^{+}$

D.  ${}_{20}{}^{42}C{a}^{2+}$

C

Which is correct for ${}_{16}^{34}{\text{S}}^{2-}$?

D

93 % of the candidates deduced the correct numbers of protons, neutrons and electrons in the sulfide ion.