Complete and balance the following chemical equations. Identify the reaction type as: combination, decomposition, single replacement, double replacement, or combustion. Products:
Magnesium Oxide + Carbon dioxide.
a) MgCO₃ (Heat is supplied to the reaction (triangle over a arrow) -> Reaction type:

Products:
Aluminum Oxide
b) Al + O₂ -> Reaction type:

Solution:-1

It is a thermal decomposition reaction

Solution:-2:-

It is a combination reaction.

Explanation:

They are indeed placed from the far left hand side of the periodic table in almost the same column. If you step around the table between left to right, the movement of electrons rises by one. When you progress down the line, the number of power increases by the one.