In the presence of anhydrous  phenol form salicyladehyde. It is Gattermann-aldehyde reaction.

Thus, 

Oxalic acid on reaction with glycerol at 530K temperature furnishallyl alcohol.

When glycerol reacts with HI iodide is obtained

 is known as Lucas reagent. Lucas test is used for the distinction between primary, secondary and tertiary alcohols.
The tertiary alcohol reacts immediately with Lucas reagent producing turbidity. The secondary alcohol gives turbidity within 5-10 min and primary alcohol doesn’t give turbidity at all at room temperature. In the given alternates, 2-hydroxy-2-methyl propane is alcohol, so it is more reactive.

General formula for alcohols is  Primary alcohols have  Secondary Alcohols have  and tertiary alcohols have 

  (Aldehyde and acid of same carbon atoms)
  (Acid of less carbon atom)

 gives iodoform test.

Electron withdrawing groups (like  increase the acidity of phenols by stabilising corresponding phenoxide ion. The effect of  group will beminimum at m-position due to lack of increased delocalisation of electrons in it. Hence, m-nitrophenol is the weakest acid among these.

4 alcohols (butan-1-ol; butan-2-ol; 2-methyl butan-1-ol; 2-methyl butan-2-ol) and 3 ethers (diethyl ether, methyl-propyl ether and methyl isopropyl ether).

Both shows H-bonding, however the increase in hydrophobic character (due to two alkyl groups in ether), the H-bonding weakens.

Alcohols are more acidic than alkynes but less acidic than water thus, the correct order of acidity is