
Here we go ~
Energy difference btween the two electronic states can be expressed as :

[ h = planks constant,
= frequency ]




Answer:
4.4 mol.
Explanation:
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In this case, since the formula for calculating the molarity is:

Whereas n stands for moles and V for the volume in liters; we can solve for n as shown below when we are given the volume and the molarity:

Thus, we plug in the given data to obtain:

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Oxidation number of an atom is the charge that atom would have if the compound is composed of ions. In neutral substances that contains atoms of one element the oxidation number of an atom is zero. Thus atoms in O2, Ni2, and aluminium all have oxidation number of zero.
In this case, Ni2, the oxidation number of Ni atom is zero,
for NiO4-, assuming oxidation number of Ni is x
(x ×1) + (-2 × 4) = -1
x = + 7
Therefore, the oxidation number goes from 0 to +7