Which of the answer choices best describes elements? homogeneous mixtures, always solid, pure substances, very dense.

Option (c) is the correct answer.

Explanation:

An element is defined as the substance that consists of same type of atoms. Also, it can never be broken down or divided into simpler substances.

For example, a sodium metal will contain only atoms of sodium and no other element.

Hence, elements are pure substances because they have only one type of atoms. An element can be present in solid, liquid or gaseous state.

A homogeneous mixture is defined as the mixture that contains even distribution of solute particles into the solvent.

For example, salt in water is a homogeneous mixture.

Thus, we can conclude that pure substances best describes elements.

d: the voltage of the secondary coil is less than that of the primary coil.

im not suree sorry if wrong

  the   balanced   equation   for   reaction of   ca metal   with   o2 to   produce   cao   is as below

2 ca+ o2→ 2 cao2

  explanation

the reaction is   balanced     since the   number of atoms   in reactant side is   equal to   number of atoms   in   product side.   for   example   they   are 2   atom of   ca in   reactant   side   and   2   atoms of ca   in   the product side.

  the   process   is a   meet the   requirement   of   redox   reaction because :     calcium   is   oxidized   from   oxidation state 0   to 2+   while   oxygen   is reduced from   oxidation   state   0   to 2-