The denticity of the ligand present in the Fehling's reagent is ___________.

In the following reaction

The $$\%$$ yield for reaction I is $$60 \%$$ and that of reaction II is $$50 \%$$. The overall yield of the complete reaction is __________ $$\%$$. [nearest integer]

The number of chiral alcohol(s) with molecular formula C₄H₁₀O is ________.

In the given reaction,

the number of sp² hybridised carbon(s) in compound 'X' is ________.