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Question: The mole fraction of \(NaCl\), in a solution containing 1 mole of \(NaCl\) in 1000g of water: A. 0...

The mole fraction of NaClNaCl, in a solution containing 1 mole of NaClNaCl in 1000g of water:
A. 0.0177
B. 1.001
C. 0.5
D. 0.244

Explanation

Solution

Hint: For solving this question, first we have to find the ratio of (No. of moles of NaClNaCl) to (No of moles of whole solution). And then we have to use the formula for calculating mole fraction i.e;
Mole fraction=no. of moles of NaClno. of moles of Solution\dfrac{{no.\,of\,moles\,of\,NaCl}}{{no.\,of\,moles\,of\,Solution}}

Complete step-by-step answer:
No. of moles of H2O{H_2}O = WeightMolecular.Mass\dfrac{{Weight}}{{Molecular.Mass}} =100018\dfrac{{1000}}{{18}} ​ =55.55
No. of moles of NaCl= 1

Mole fraction of NaCl=no. of moles of NaClno. of moles of NaCl+no. of moles of H2O\dfrac{{no.\,of\,moles\,of\,NaCl}}{{no.\,of\,moles\,of\,NaCl + no.\,of\,moles\,of\,{H_2}O}}
=155.55+1\dfrac{1}{{55.55 + 1}}
=0.01768≈\approx 0.0177
Thus option A “0.0177” is the correct answer to the problem.

Note: For solving this question, one should know the molecular mass of an element and should also know how to calculate the no. of moles.