Questions

The boiling point of the compounds depend on the number of carbons in them. Hexane has 6, Pentane has 5 and Propane has 3 carbons. As Hexane is with 6 carbons it has highest boiling point and next Pentane with 5 and lowest Propane with 3. 

Electronegativity refers to the ability of an atom to attract shared electrons in a covalent bond. The higher the value of the electronegativity, the more strongly that element attracts the shared electrons.

Electronegativity increases from bottom to top in groups, and increases from left to right across periods. Thus, fluorine is the most electronegative element and lithium is the least.

It takes 248 yrs for Pluto to orbit the Sun.

We know that, there are 7 continents in the world. They are :

Asia, Africa, Australia, North America, South America, Europe and Antarctica.

Africa - 53 countries

Asia - 48 countries

Europe - 45 countries

Antarctica - 0 countries

Hence, the continent Africa has most number of countries with 53 countries and in second place Asia has 48 , third Europe has 45 countries.