Question

Sodium - 24 has a hourly decay rate of 5%

how many grams of a 900 g sample will remain after 90 hours ?
Round the answer to two decimal places

• 7.03 g
•7.50 g
•8.90 g
•28.13 g

Please Hurry !

Answer 1

The amount of sodium- 24 remain after 90 hours of decay is 8.90 gram

Explanation:

Given as :

The amount of sodium-24 = 900 gram

The decay rate of sodium is 5 %

The time period for its decay = 90 hours

`Final value of sodium -24 = initial value *  (1 - (Rate)/(100))^(Time)`

Or,
`Final value of sodium -24 = 900 gram *  (1 - (5)/(100))^(90)`

Or, Final value of sodium -24 = 900 g ×
`(0.95)^(90)`

Or, Final value of sodium -24 = 900 g ×
`(9.88)^(-3)`

∴ Final value of sodium -24 = 8.899 gram

Hence The amount of sodium- 24 remain after 90 hours of decay is 8.90 gram Answer