Its b.functional paragraph because writers use this for interest presents and special effects
Line spectra are obtained when individual elements are heated using a high-voltage electrical discharge. This heating causes excitation of the element and a subsequent emission of distinct lines of colored light are obtained. Each element has its own unique emission line spectrum; therefore, if any of the tested substances were the same, their spectra would match. However, this is not the case so none of the substances are the same.
hope it helps!

Heat capacity of body 1 :

Heat capacity of body 2 :

it's given that, the the head capacities of both the objects are equal. I.e


Now, consider specific heat of composite body be s'
According to given relation :



[ since,
]




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The tangent looks good.
The curve is a bit crooked, at the 0.9 and 1.
But overall, cool graph.