White phosphorus on reaction with concentrated NaOH solution in an inert atmosphere of $\mathrm{CO}_{2}$ gives phosphine and compound $(\mathrm{X})$. $(\mathrm{X})$ on acidification with HCl gives compound $(\mathrm{Y})$. The basicity of compound $(\mathrm{Y})$ is :

JEE Main · 2020 · 08 Jan 2020 · Shift 2 · p-Block Elements

White phosphorus on reaction with concentrated NaOH solution in an inert atmosphere of

CO_{2}

gives phosphine and compound

(X)

(X)

on acidification with HCl gives compound

(Y)

. The basicity of compound

(Y)

is :

(A)2
(B)4
(C)3
(D)1✓ Correct

Answer: (D)

Solution

White phosphorus warmed with concentrated

NaOH

gives phosphine and sodium hypophosphite,

P X_{4} + 3 NaOH + 3 H X_{2} O PH X_{3} + 3 NaH X_{2} PO X_{2}

, so

X

NaH X_{2} PO X_{2}

. Acidifying with

HCl

liberates hypophosphorous acid,

H X_{3} PO X_{2}

, which is

Y

. In

H X_{3} PO X_{2}

the phosphorus carries one

P = O

, two

P - H

bonds and a single

- OH

group, and only that one

- OH

can ionise, so the basicity of

Y

1

JEE Main · 2020 · 08 Jan 2020 · Shift 2 · Single correct option

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