Question -
Barring Helium, the melting and boiling points of every noble gas lie within a range of 10 degrees Celsius – True or false?
Options:
A .  True
B .  False
C .  Neon, Argon, Krypton and Xenon are used to impart different colours in “neon lights”
D .  Liquid Helium can be used to cool apparatus close to 1 K. This is particularly impressive to cool superconducting magnets that produce very high magnetic fields
E .  None of the above
Answer: Option A : A All these noble gases are monoatomic gases at room temperature. The atomicity is explained by the stable valence electron configuration. Can you recall what the valence configuration in general is? These elements are gases at room temperature because in the liquid/solid states, very weak dispersion forces hold these atoms together. So to reach such states, large negative Celsius temperatures are required. Let us look at the values: NoblegasMeltingpoint(∘C)Boilingpoint(∘)CNumberofelectronsHe−−2692Ne−249−24510Ar−189−18618Kr−157−15236Xe−112−10954Rn−71−6286 As you can see, the largest range between melting point and boiling point is for Rn and this is <10 degrees Celsius. Hence the statement in the question is true!
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