Description : A radioactive isotope has a half-life of 10 days. If today there are 125 g of it left, what was its original weight 40 days earlier (a) 600 g (b) 1000 g (c) 1250 g (d) 2000 g
Last Answer : Half life = 10days The formula which is, 1/(2)^n × original weight = Weight left today. To obtain the value of n = divide no of days by half life ie.,n= 40/10= 4 n=4 So, 1/(2)^n × original Weight = 125g 1/(2)^4 × Original weight = 125 Original weight = 16×125 = 2000g