Chloroform for anesthetic purposes is tested for its purity with the reagent

The $C-X$ bond is strongest among the following:

Which of the following reactions is expected to take place by the $S_N2$ mechanism?

Which of the following chloro-compounds shows complete inversion of configuration during a reaction?

Identify the correct order for the given property for the following compounds. Choose the correct answer from the options given below:
$(A)$ Boiling Point: $CH_3CH_2Cl < CH_3CH_2CH_2Cl < CH_3CH_2CH_2CH_2Cl$
$(B)$ Density: $CH_3CH_2Br < CH_3CH_2Cl < CH_3CH_2I$
$(C)$ Boiling Point: $CH_3CH_2Br < (CH_3)_2CHBr < (CH_3)_3CBr$
$(D)$ Density: $CH_3CH(I)Br < CH_3CH_2CH_2Br < CH_3CH(Br)Cl$
$(E)$ Boiling Point: $CH_3CH_2CH_2CH_2Cl > (CH_3)_2CHCH_2Cl > (CH_3)_3CCl$

Which among the following metals is involved in the preparation of a Grignard reagent?