question_answer 8)

                Three vessels of equal capacity have gases at the same temperature and pressure. The first vessel contains neon (monatomic), the second contains chlorine (diatomic), and the third contains uranium hexafluoride (polyatomic). Do the vessels contain equal number of respective molecules ? Is the root mean square speed of molecules the same in the three cases ? If not, in which case is  the largest  

Answer:

                All the three vessels (at the same temperature and pressure) have same volume. So, in accordance with the Avogadro's law, the three vessels will contain equal number of respective molecules, being equal to Avogadro's number                 As, i.e. at a given temp.                                 Therefore, rms speed of molecules will not be the same in the three cases.                As neon has the smallest mass, therefore, rms speed will be the largest in case of neon.