It turns chemical into electricity
<span>The question does not mention the brand or size of antacid tablets, but some research in the internet shows that for a very common brand, Alka Seltzer, that it takes about 4 tablets to produces 60 mL of gas. So for 120mL it will take 120/60 x 4 or 8 tablets to produce 120 mL of CO2 gas.</span>
Answer:
If a reaction produces a gas such as oxygen or carbon dioxide, there are two ways to measure the reaction rate: using a gas syringe to measure the gas produced, or calculating the reduction in the mass of the reaction solution.

☃️ Chemical formulae ➝ 
How to find?
For solving this question, We need to know how to find moles of solution or any substance if a certain weight is given.

Solution:
❍ Molecular weight of 
= 2 × 126.90
= 253.80
= 254 (approx.)
❍ Given weight: 12.7
Then, no. of moles,
⇛ No. of moles = 12.7 / 254
⇛ No. of moles = 0.05 moles
⚘ No. of moles of Iodine molecule in the given weight = <u>0.05</u><u> </u><u>moles </u>
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An open system<span> is a system that has external interactions.</span>