2015-11-06T16:06:20+05:30

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Molecular weight or mass of  NinHydrin =  9 * 12 + 6 * 1 + 16 * 4
= 178

As per Avogadro's law we have that one mole ( 178 gms) of NonHydrin contains N = avogadro number ie., 6.023 * 10²³ molecules.

so number of molecules in 7.4 gms are:  6.023 * 10²³ * 7.4 / 178
= 2.502 * 10²²
2015-11-06T16:32:16+05:30

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Chemical formula of Ninhydrin is C₉H₆O₄
Molar mass = 9×12 + 6×1 + 4×16 = 108+6+64 = 178g

178 gram of Ninhydrin contains = 1 mole = 6.022×10²³ molecules
1 gram of Ninhydrin contains = 6.022×10²³/178 molecules
7.4 gram of Ninhydrin contains = 7.4×6.022×10²³/178 = 2.561×10²² molecules

So number of molecules in 7.4 gram Ninhydrin is 2.561×10²² molecules.