i get the concept but not when they add the reaction so a explanation and answer would help will give brain list

answer: mole of the gas

answer: mole of the gasexplanation:

answer: mole of the gasexplanation: this is because 1 mole of a gas is 22.4dm³, which is use in ideal gas

The answer is not c

Radon-222 or rn-222 has a half-life of 3.82 days. to determine the fraction of an original sample of rn-222 that remains unchanged after 7.646 days, we calculate the amount of rn-222 remaining after 7.646 days and divide it with the original amount. using 1 gram as a basis and using half-life calculation methods, we can determine that  0.249 or 0.25  grams of rn-222 will remain, and thus the fraction remaining is 0.25 or 1/4.

Idon’t really understand the question i’m sorry i can’t