Given a positive number N, when N is rounded by a certain method (for convenience, call it Method Y), the result is \(10^n\) if and only if n is an integer and \(5*10^{n - 1} \le N < 5*10^n\). In a certain gas sample, there are, when rounded by Method Y, \(10^{21}\) molecules of \(H_2\) and also \(10^{21}\) molecules of \(O_2\). When rounded by Method Y, what is the combined number of \(H_2\) and \(O_2\) molecules in the gas sample?

(1) The number of \(H_2\) molecules and the number of \(O_2\) molecules are each less than \(3*10^{21}\).
(2) The number of\(H_2\) molecules is more than twice the number of \(O_2\) molecules.



OA C

Source: Official Guide