The temporary hardness of a water sample is due to compound X. Boiling this sample converts X to compound Y. X and Y, respectively, are :

The metal that gives hydrogen gas upon treatment with both acid as well as base is :

The correct statements among (a) to (d) are :
(a) saline hydrides produce H₂ gas when reacted with H₂O.
(b) reaction of LiAlH₄ with BF₃ leads to B₂H₆.
(c) PH₃ and CH₄ are electron - rich and electron - precise hydrides, respectively.
(d) HF and CH₄ are called as molecular

The synonym for water gas when used in the production of methanol is :