When the difference in electron-attracting ability between atoms in a chemical bond is , the atoms in the bond will have no significant partial charges. we call this type of bond a nonpolar covalent bond.

Very small.

Explanation:

The electron-attracting ability is the electronegativity of an atom, and it's the ability that an atom has to "push" by it the electron in a bond. When there is a very large difference in this ability, the atom with low electronegativity will lose electrons, and the other will gain electrons and an ionic bond will be formed, It happens between metals and nonmetals.

But, when that difference is not so large, the atoms must share the electrons, and a covalent bond is formed. When the difference in electronegativity can't be disregarded, the atom with high one will have a partial negative charge, and the other a partial positive charge and the covalent bond will be polar.

When the difference in electronegativity is very small (close to 0), partial charges will not be formed, and the covalent bond will be nonpolar.

out of these options:

ability to burn paper

pure sodium reacting violently with water

the boiling point of water

helium does not tend to react with anything

i would say this is a physical property:

helium does not tend to react with anything

why? :

i said helium does not tend to react with anything because well, it reacts to ! but ability to burn paper, pure sodium reacting violently with water, & the boiling point of water are chemical or

physical properties: the properties of a substance that can be observed without changing the chemical makeup of the substance

chemical properties: properties of a substance relating to the chemical nature and reactivity of the substance