The atomic number of Ni is given as 28. So, as we can see, there will be 28 electrons located in the Ni atom.
Here it’s given that the charge on the complex [Ni(CN)4]2- is (-2). Each cyanide ion has a charge of (-1). So, we can say that Ni atoms are in a +2 oxidation state. Now, we will first write the ground state electronic configuration of Ni2+.
Ground state electronic configuration of Ni2+ : [Ar]3d8

Now, the excited state electronic configuration of Ni2+ can be given as[Ar]3d8 but the arrangement of electronics is as below.

Here, we’ll notice 1 d-orbital, 1 s-orbital, and 3 p-orbitals become vacant. The 8 electrons present in the d-orbitals are coupled together.
- So, the cyanide ligands produce the pair of electrons to the vacant orbitals of the nickel atom.
- We can see that there are 4 cyanide ligands present in that complex. So, four produce two electrons each. So, a total of four orbitals will get the electron pairs by each.
- First the orbital with the lower energy level gets] the electrons. So, electron pairs are produced in one d-orbital, 1 s-orbital, and 2 p-orbitals and so on, 4 cyanide ligands bind to the metal.
- So, we can say that the hybridization of the complex element is dsp2
So, the correct answer is (C).

A sphere of radius R is cut from a larger solid sphere of radius 2R as shown in the figure. The ratio of the moment of inertia of the smaller sphere to that of the rest part of the sphere about the Y-axis is : 
A constant voltage of 50 V is maintained between the points A and B of the circuit shown in the figure. The current through the branch CD of the circuit is :
The current passing through the battery in the given circuit, is: 
Given below are two statements:
Statement I: The primary source of energy in an ecosystem is solar energy.
Statement II: The rate of production of organic matter during photosynthesis in an ecosystem is called net primary productivity (NPP).
In light of the above statements, choose the most appropriate answer from the options given below:
A coordination compound holds a central metal atom or ion surrounded by various oppositely charged ions or neutral molecules. These molecules or ions are re-bonded to the metal atom or ion by a coordinate bond.
A coordination entity composes of a central metal atom or ion bonded to a fixed number of ions or molecules.
A molecule, ion, or group which is bonded to the metal atom or ion in a complex or coordination compound by a coordinate bond is commonly called a ligand. It may be either neutral, positively, or negatively charged.