question_answer

Modern vacuum pumps can evacuate a vessel down to a pressure of \[4.0\times {{10}^{-15}}\]atm. at room temperature (300 K). Taking \[\text{R=8}\text{.0J}{{\text{K}}^{\text{-1}}}\text{mol}{{\text{e}}^{\text{-1}}}\text{,1atm=1}{{\text{0}}^{\text{5}}}\text{Pa}\]and\[{{\text{N}}_{\text{Avogadro}}}=6\times {{10}^{23}}\text{mol}{{\text{e}}^{-1}},\]the mean distance between molecules of gas in an evacuated vessel will be of the order of:                   [JEE Main Online Paper ( Held On 09 Apirl  2014  )

A) 0.2 mm                                

B) 0.2 mm

C) 0.2 cm                  

D) 0.2 nm