Decide which element probably has a boiling point most and least similar to the boiling point of potassium.
(a) thallium
(b) strontium
(c) helium
(d) sodium

Explanation:

The boiling point of Potassium is most similar to the element sodium , since , both the elements belong to the same group i.e. , the group one , Hence , the most of the physical chemical properties are same , irrespective of some exceptions .

Hence , the Boiling point of Potassium and sodium are the same .

The boiling point of Potassium is least similar to the element helium , since , both the elements belong to different groups , Since , Helium has a negative boiling point and is one of the most stable element , being a noble gas .