Compound A with molecular formula C4H9Cl shows two 13C NMR resonances. Compound B is an isomer of compound A; it shows four 13C NMR resonances, and in the spin-coupled mode the resonance farthest downfield is a doublet. Required:
Identify compound A.

c. heat could easily travel through the molecules in the air and escape/enter the flask. removing the air slows down the heat transfer.  

metals are good conductor of electricity. it has free electrons on their surface. according to electron pool theory, each atom present in a metal crystal losses all of its valence electron and as a result a pool of free is form. these pool of electrons are free to move and   conduct electricity easily   while making metal as good conductor.

the correct answer is a. the ability of electrons to flow throughout the metal.

if it's not useful, feel free to report for mistake in answer.