Electronegativity generally increases moving from left to right across a period generally decreases moving from left to right across a period generally increases moving from right to left across a period generally decreases moving from right to left across a period

generally increases moving from left to right across a period

Explanation:

Electronegativity is defined as the property of an element to attract a shared pair of electron towards itself. The size of an atom decreases as we move across the period because the electrons get added to the same shell and the nuclear charge keeps on increasing. Thus the electrons get more tightly held by the nucleus.

As, the size of an element decreases, the valence electrons come near to the nucleus. So, the attraction between the nucleus and the shared pair of electrons increases.

Hence, the correct statement is electronegativity generally increases moving from left to right across a period

i believe it is 40–40–20%

explanation:

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