Answer the question on the basis of passage given below:

In the periodic table, the d-block contains the elements of group 3 to 12. The d-orbitals are progressively filled in each of the four long periods. The elements of d-block referred as transition metals have partially filled d-orbitals and exhibit certain characteristic properties such as variety of oxidation states, formation of coloured ions, act as catalyst and slow paramagnetic behavior.

The two inner transition metals series 4f and 5f are known as Lanthanoids and Actinoids respectively. The lanthanoids resemble one another more closely as compared to ordinary transition in any series.

The bonds present in the structure of dichromate ion is:

Six equivalent \(Cr–O\) bonds and one \(Cr–O–Cr\) bond

The correct answer is option (4)Six equivalent \(Cr–O\) bonds and one \(Cr–O–Cr\) bond

The dichromate ion, \(Cr_2O_7^{2-}\), has a structure in which two tetrahedral chromate units, \(CrO_4^{2-}\), are linked together by a shared oxygen atom. This gives the dichromate ion a distorted octahedral structure, with six Cr–O bonds and one Cr–Cr bond

Here is a diagram of the dichromate ion structure:

The Cr–O-Cr bond is the longest bond in the dichromate ion, and it is also the weakest bond. This is why the dichromate ion is easily reduced to the chromate ion, \(CrO_4^{2-}\).