What does an element's group number tell you about an element's chemical and physical properties ?

The chemical properties of elements are determined by their valence shell electronic configuration.

for example; the group 15 ( nitrogen family ),

The valence shell ( outermost shell ) electronic configuration of is ns2np3 , which clearly shows that all the elements have the tendency to make same kind if bonds with a common element.

That is, consider the hydrates of the group, it is NH3 ( ammonia ),PH3 (phosphine ), AsH3 (arsine ) , SbH3 ( stibine ) etc. They are having the same chemical formula and same type of bond (covalent bond )

The physical properties include melting point, boiling point, density etc.

Here for the same nitrogen family, all elements except nitrogen are solids in room temperature whereas nitrogen is gas.

Your answer is c. explanation: plasma  is the fourth state of matter, derived from the gaseous state of matter.  plasma  can contain free  electrons  and/or  ions. while  plasma is never neutral, it can either be positively or negatively charged.  gases, however, are electrically neutral.

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