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

From figure given in question

(as Ði = Ðr)

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

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).

 gives iodoform test.

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

 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.

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

and
Yellow, orange and red have higher wavelength than green, so m will be less for these rays, consequently critical angle for these rays will be high, hence if green is just totally internally reflected then yellow, orange and red rays will emerge out.

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

Thus, 

When glycerol reacts with HI iodide is obtained