21. Which type of reaction is shown below? BaCl2(aq) + K2CO3(aq) → BaCO3(s) + 2 KCl(aq)
A)Decomposition
B)Double replacement
C)Single replacement
D)Combustion

The correct answer is B) Double displacement.

This is because the Barium (Ba), which has a positive charge, got rearranged to bond with the carbonate (CO3), which has a negative charge. Also, the potassium (K), which has a positive charge, bonded with the chlorine (Cl), which has a negative charge.

It helps to remember that when there is a double replacement there are 4 elements/molecules in the reactants and 4 in the products that get rearranged.

Hope this helps!