The sum of coordination number and oxidation number of the metal M in the complex [M(en)₂(C₂O₄)]Cl (where en is ethylenediamine) is

The hybridization involved in complex [Ni(CN)₄]^$$2-$$ is (At. No. Ni = 28)

Number of possible isomers for the complex [Co(en)₂Cl₂]Cl will be (en = ethylenediamine)

Gadolinium belongs to 4f series. Its atomic number is 64. Which of the following is the correct electronic configuration of gadolinium?