Question

which balances the equation mg + o₂ → mgo?
o mg + 2o₂ → 4mgo
o 2mg + 2o₂ → 2mgo
o 2mg + o₂ → 2mgo
o 2mg + 2o₂ → 4mgo

Explanation:

Step1: Count atoms on reactant side

On the left - hand side of the unbalanced equation $Mg + O_2
ightarrow MgO$, we have 1 Mg atom and 2 O atoms.

Step2: Analyze each option

• Option 1: $Mg + 2O_2

ightarrow4MgO$. Reactant side has 1 Mg and 4 O, product side has 4 Mg and 4 O. Not balanced.

• Option 2: $2Mg + 2O_2

ightarrow2MgO$. Reactant side has 2 Mg and 4 O, product side has 2 Mg and 2 O. Not balanced.

• Option 3: $2Mg+O_2

ightarrow2MgO$. Reactant side has 2 Mg and 2 O, product side has 2 Mg and 2 O. Balanced.

• Option 4: $2Mg + 2O_2

ightarrow4MgO$. Reactant side has 2 Mg and 4 O, product side has 4 Mg and 4 O. Not balanced.

Answer:

$2Mg + O_2
ightarrow2MgO$ (the third option in the multiple - choice list)