D Aluminium, chromium and manganese are all moderately reactive metals. Use the following information to arrange them in the correct reactivity
series order. Start with the most reactive one.
Chromium is manufactured by heating chromium(III) oxide with aluminium.
If manganese is heated with aluminium oxide there is no reaction.
- If manganese is heated with chromium(III) oxide, chromium is produced,

a compound is a molecule made of atoms from different elements.

a. by the combination of an unlimited number of elements

  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-

personal, she chose to do it.

colorless gas, exhibiting a blue glow when placed in an electric field

b) solid

its a type of rock