Decreasing order (first having highest and then other following it) of mass of pure NaOH in each of the aqueous solution
(P) 50 gm of `40%(w//w)` NaOH
(Q) 50 gm of `50%(w//w)` NaOH `[d_("soln.")=1.2gm//ml]`
(R) 50 gm of 20 M NaOH `[d_("soln").=1gm//ml]`

Options

A. (P), (Q), (R)
B. (R), (Q), (P)
C. (Q), (R), (P)
D. All contain same wt of NaOH

Answer

B