Initial number of not decayed nucleis 5cdot 10^10 Half-life is equal to 200 seconds. In 400 seconds the number of not decayed nuclei is equal to Bbibepute onMH orger. a. 1.25cdot 10^10 b. 2.5cdot 10^10 C. 25cdot 10^9 d. 0 e. 5cdot 10^9

The decay of nuclei follows the exponential decay law, and the number of undecayed nuclei after a certain time can be calculated using the formula: Where:- is the initial number of nuclei,- is the half-life,- is the elapsed time.### Given:- ,- ,- .Substitute these values into the formula: Simplify the exponent: So: ### Final Answer:**a. **