Questions

DPI [Dots Per Inch] is a measurement of output quality of printer resolution. It represents number of ink dots the printer can place in an area of one square inch. The lesser the DPI the less sharper the image and vice versa.

Therefore, a printer that may have 400 DPI, a printer that can print 400 x 400 per square inch or 1,60,000 dots per inch.

The letter 'P' sounds same as the vegetable 'PEA'.

Hence P is an alphabet which is a vegetable.

Hybridisation of Ni is e-  

Unpaired 3d8in  is 2 

So $$\begin{gathered} Ω = n(n+2)BM \\ =2x4 = 8 = 2.82BM \end{gathered}$$

When atoms react they do so in order to reach the lowest energy, which is the most stable. The electrons orbitals will overlap in the way that reduces the energy the most. Orbitals of similar energy will produce the greatest stabilisation.The answer you gave isn't the whole story, it depends what species is reacting with what. The effective nuclear charge on the atom will affect the energy of the valance electrons.

Hence, the reactivity of an atom arises from the existence of unpaired electrons in the valence shell.