Select the incorrect statement

$(a)$ $PCl_5$ form weak monobasic acid during hydrolysis
$(b)$ In $B_3N_3H_6$ nucleophile attack on $B-$ atom
$(c)$ $Al_2Cl_6$ is a polar and planar molecule
$(d)$ In $AlF_3$, hybridisation of $Al$ is $sp^2$

When metal $X$ is treated with sodium hydroxide, a white precipitate $(A)$ is obtained, which  is soluble in excess of $NaOH$ to give soluble complex $(B)$. Compound $(A)$ is soluble in dilute $HCl$ to form compound $(C)$. The compound $(A)$ when heated strongly gives $(D)$, which is used to extract metal. Identify $(X), (A), (B), (C)$ and $(D)$. Write suitable equations to support their identities.

A group $13$ element $'X'$  reacts with chlorine gas to produce a compound  $XCl_3. XCl_3$ is electron deficient and easily reacts with $NH_3$ to form $Cl_3X \leftarrow NH_3$ adduct, however, $XCl_3$ does not dimerize. $X$  is

The liquefied metal which expands on solidification is