Glucose when reduced with HI and red phosphorus gives

A compound X when passed through dil. H_(2)SO_(4) containing HgSO_(4) gives a compound Y which on reaction with HI and red phosphorus gives C_(2)H_(6) . The compound X is

When ethanol is heated with HI and red phosphorus, it gives

When ethanol is heated with HI and red phosphorus it gives

Glucose is reduced by HI gives

Glucose is reduced by red P/HI

Red and yellow phosphorus are: