These gases all have similar properties under standard conditions: they are all odorless, colorless, monatomic gases with very low chemical reactivity. The six noble gases that occur naturally are helium (He), Neon (Ne), Argon (Ar), Krypton (Kr), Xenon (Xe), and Radon (Rn).
Answer:
Thus, the radius of the helium atom in nanometers is - 0.031 nm
Explanation:
Given that:-
The radius of the helium atom = 31 pm
Considering the conversion of length in pm to the length in nm as:-
1 pm = 0.001 nm
So,
Applying the above conversion factor in the radius of helium atom as:-
Radius = 
nm = 0.031 nm
<u>Thus, the radius of the helium atom in nanometers is - 0.031 nm</u>
The energy<span> per </span>photon<span> is proportional to the </span>frequency<span> of the radiation when considered as waves, ie inversely proportional to the </span>wavelength. Double the wavelength<span>, halve the </span>photon energy<span>. This means that long </span>wavelength<span> radiation (radio waves) has low </span>photon energy<span> and so does not penetrate matter.</span>
