Hydrolysis of sucrose gives :

Which of the following phenomena is $NOT$ explained by the open chain structure of glucose?

Four carbohydrates: glucose,lactose,sucrose,and starch are present. Different tests are carried out with these $4$ carbohydrates separately. The following observations are made:
$(a)$ Heated: It is charred.
$(b)$ $I_2$ solution: No violet colour.
$(c)$ Fehling solution: Reddish brown precipitate is observed.
$(d)$ It does not reduce copper$(II)$ acetate to $Cu_2O$. No red precipitate is observed in $5 \ min$.
Which carbohydrate satisfies all the above observations?

What is the molecular formula of glyceraldehyde?

What is the total number of $-OH$ groups present in a ribonucleoside?

An organic compound gives a positive result for Molisch's test as well as Benedict's test,but it does not give a positive result for Seliwanoff's test. Most probably,it is: