• # question_answer A radioactive nucleous decays according to following series$X\xrightarrow{\alpha }{{X}_{1}}\xrightarrow{\beta }{{X}_{2}}\xrightarrow{\alpha }{{X}_{3}}\xrightarrow{\gamma }{{X}_{4}}$. If the a tomic number and atomic weight of the parent element X are 72 and 180 respectively then the atomic number and atomic mass of ${{X}_{4}}$ are respectively: A)  $70,172$                   B)  $69,171$C)  $69,172$                   D)  $68,172$

Series would be follows: $_{72}^{180}X\xrightarrow{\alpha }_{70}^{176}{{X}_{1}}\xrightarrow{\beta }_{69}^{172}{{X}_{2}}\xrightarrow{\alpha }_{69}^{172}{{X}_{3}}\xrightarrow{\gamma }_{69}^{172}{{X}_{4}}$