Question

A mixture of 2×10^21 molecules of P and 3×10^21 molecules of Q weighs 0.6g. if the molecular mass of P is 45 the molecular mass of Q will be..
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Answer 1

Answer:90 gm

Explanation : According to Avogadro rule, 6*10power23 weigh the molecular weight of the element.

So, 45 gm of P have 6*10power23 electrons

Hence, 2*10power21 molecules weigh

(2*10power23)/(6*10power23)*45

=0.15 gm

Molecular weight of Q = Molecular weight of (P+Q) - Molecular weight of P

= 0.60 - 0.15 = 0.45

So 3*10power21 molecules weigh 0.45 gm

Hence 6*10power23 molecules weigh is molecular weight, that is

6*10power23/3*10power21(0.45) = 90gm