28. The density of compound XHn as gas is 2.393 times that of O2. If 0.01 mol of this compound reacts with excess O2, 0.36 g of water is generated. The atomic weight of element X is: (A) 69.72 g/mol (B) 72.55 g/mol (C) 74.92 g/mol (D) 78.97 g/mol (E) 83.80 g/mol