I believe the answer is: in order not to write very big or very small number values
The chemical equation that represents the reaction of an Arrhenius acid and an Arrhenius base is 1) HC2H3O2 (aq) + NaOH (aq) ---> NaC2H3O2 (aq) + H2O (I)
Answer: Neutral Value
Explanation: pH of the blood is maintained at 7.0 to 7.5that is neutral value.
This is because if the pH of the is lower than the maintained value then it will become acidic .
Acidic pH can cause the medical urgency known as acidosis leading to vomiting, diarrhea etc.
If the pH becomes higher, then the blood will become basic in nature and it can also leas to the death of the person.
That is why the pH of the blood is maintianed at neutral value of 7.0 to 7.5
Step 1 - Discovering the ionic formula of Chromium (III) Carbonate
Chromium (III) Carbonate is formed by the ionic bonding between Chromium (III) (Cr(3+)) and Carbonate (CO3(2-)):

Step 2 - Finding the molar mass of the substance
To find the molar mass, we need to multiply the molar mass of each element by the number of times it appears in the formula of the substance and, finally, sum it all up.
The molar masses are 12 g/mol for C; 16 g/mol for O and 52 g/mol for Cr. We have thus:

The molar mass will be thus:

Step 3 - Finding the percent composition of carbon
As we saw in the previous step, the molar mass of Cr2(CO3)3 is 284 g/mol. From this molar mass, 36 g/mol come from C. We can set the following proportion:

The percent composition of Carbon is thus 12.7 %.