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 :

Evaluate the following statements for their correctness.

A. The elevation in boiling point temperature of water will be same for $0.1 \mathrm{M} \, \mathrm{NaCl}$ and $0.1 \mathrm{M}$ urea.

B. Azeotropic mixtures boil without change in their composition.

C. Osmosis always takes place from hypertonic to hypotonic solution.

D. The density of $32 \% \, \mathrm{H}_{2} \mathrm{SO}_{4}$ solution having molarity $4.09 ~\mathrm{M}$ is approximately $1.26 \mathrm{~g} \mathrm{~mL}^{-1}$

E. A negatively charged sol is obtained when KI solution is added to silver nitrate solution.

Choose the correct answer from the options given below :

Arrange the following orbitals in decreasing order of energy.

A. $\mathrm{n}=3, \mathrm{l}=0, \mathrm{~m}=0$

B. $\mathrm{n}=4, \mathrm{l}=0, \mathrm{~m}=0$

C. $\mathrm{n}=3, \mathrm{l}=1, \mathrm{~m}=0$

D. $\mathrm{n}=3, \mathrm{l}=2, \mathrm{~m}=1$

The correct option for the order is :

In Dumas method for the estimation of $\mathrm{N}_{2}$, the sample is heated with copper oxide and the gas evolved is passed over :