Question

X is an atom of an element in which 4th shell is the valence shell and the number of electrons are in 1 : 1 ratio in 1st, 4th and 2nd, 3rd shells respectively. Its corresponding oxide Y on hydrolysis gives Z. Explain the changes that take place when phenolphthalein and methyl orange are added to Z separately.

Answer 1

As the element burns with a brick red flame, it is calcium with electronic configuration 2, 8, 8, 2
`underset(("X"))(Ca) + O_(2) rarr underset(("Y"))(CaO)`
`underset(("Y"))(CaO) + H_(2)O rarr underset(("Z"))(Ca(OH)_(2))`
As `Ca(OH)_(2)` is basic in nature it turns phenolphthalein pink and methyl orange yellow.