List of top Chemistry Questions on Hydrogen Bonding asked in WBJEE

The boiling point of water is higher than liquid HF. The reason is that:
The bond angle in $NF _{3}\left(102.3^{\circ}\right)$ is smaller than $NH _{3} (107.2 \left.^{\circ}\right)$. This is because of
Blackened oil painting can be restored into original form by the action of:
An organic compound contains C = 40%, H = 6.67%, N = 46.67% and rest is oxygen. On heating, it gives NH3 along with solid residue and solid residue gives violet colour with alkaline copper sulphate solution. If molecular mass of this organic compound is 60 g, then the compound is: