In the beta decay of bismuth-214, what daughter element is produced? (you may need to refer to the periodic table in the lesson. ).

17 a tourist was planning a trip by car for travelling at some constant speed for 2.5 hours. however, he found that if he increases the speed by 20 km/h he can cover the same distance in 30 minutes less time than it was planned. what was the planned speed of the tourist, in km/h?