Answer:
The final balanced equation is :

Explanation:

Balancing in acidic medium:
First we will determine the oxidation and reduction reaction from the givne reaction :
Oxidation:

Balance the charge by adding 2 electrons on product side:
....[1]
Reduction :

Balance O by adding water on required side:

Now, balance H by adding
on the required side:

At last balance the charge by adding electrons on the side where positive charge is more:
..[2]
Adding [1] and [2]:

The final balanced equation is :

Answer: 40.1%
Explanation: The mass of calcium in this compound is equal to 40.1 grams because there's one atom of calcium present and calcium has an atomic mass of 40.1 . The molar mass of the compound is 100.1 grams. Using the handy equation above, we get: Mass percent = 40.1 g Ca⁄100.1 g CaCO3 × 100% = 40.1% Ca.
Displacement reaction is a chemical reaction in which a more reactive element displaces a less reactive element from its compound. Both metals and non-metals take part in displacement reactions. Example : Reaction of iron nails with copper sulphate solution.