The correct answer is (d) 0.0067
The explanation: Given,
Normality, N = 0.02
It is known that N = nf x M, where nf is the n-factor of equivalence and M is the molarity of the solution.
On expanding, N = nf x \(\frac{Number \, of \, moles}{volume \, of \, solution(L)}\)
For H3PO4, nf = 3 since there are 3 breakable OH bonds.
Therefore, N = 3 x \(\frac{Number \, of \, moles}{mass \, of \, solvent(kg)}\) . Here, volume of solution (1 L) can be approximated as mass of solvent (1 kg) since it is an dilute solution in water (density = 1 kg/L) implying water concentration is far greater such that amount of H3PO4 is negligible.
Now, \(\frac{Number \, of \, moles}{mass \, of \, solvent(kg)}\) = molality of solution
Thus, N/3 = 0.02/3 =0.0067 molal.