Which of the following elements have half-filled f-orbitals in their ground state?

(Given : atomic number $\mathrm{Sm}=62 ; \mathrm{Eu}=63 ; \mathrm{Tb}=65 ; \mathrm{Gd}=64, \mathrm{Pm}=61$ )

A. $\mathrm{Sm}$

B. Eu

C. $\mathrm{Tb}$

D. Gd

E. $\mathrm{Pm}$

Choose the correct answer from the options given below :

Match List I with List II

LIST I		LIST II
A.	Physisorption	I.	Single Layer Adsorption
B.	Chemisorption	II.	$20-40 \mathrm{~kJ} \mathrm{~mol}^{-1}$
C.	$\mathrm{N}_{2}(\mathrm{~g})+3 \mathrm{H}_{2}(\mathrm{~g}) \stackrel{\mathrm{Fe}(\mathrm{s})}{\longrightarrow} 2 \mathrm{NH}_{3}(\mathrm{~g})$	III.	Chromatography
D.	Analytical Application or Adsorption	IV.	Heterogeneous catalysis

Choose the correct answer from the options given below:

Which of the following compounds are not used as disinfectants ?

A. Chloroxylenol

B. Bithional

C. Veronal

D. Prontosil

E. Terpineol

Choose the correct answer from the options given below :

The Lewis acid character of boron tri halides follows the order :