In the symbol 42he, the subscript 2 is the for helium and the superscript 4 is the for helium. question 10 options: atomic mass; atomic number atomic number; atomic mass mass number; atomic number atomic number; mass number

The correct answers for this problem is:

atomic number; atomic mass

Atomic number indicates the number of protons or electrons that is located in that atom. Helium contains 2 protons or electrons hence an atomic number of 2. Meanwhile the atomic mass of 4 indicates the mass of the atom per mole.

mass number; atomic number

  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-