If an element has a half-life of 30 minutes, 3.125 gram of this element remains after 2 hours & 30 minutes if we start with 100 g of the element.
Hence, option B is correct answer.
N = N₀ [tex](\frac{1}{2})^{\frac{t}{t_{1/2}}[/tex]
where,
N = amount of remaining radioactive
N₀ = original amount of radioactive sample
t = elapsed time
[tex]t_{1/2}[/tex] = half life of the substance
Original amount of radioactive substance = 100 grams
Time elapsed = 2 hours and 30 minutes
Half life = 30 minutes
Convert hours into minutes
1 hour = 60 minutes
2 hr. 30 min = 2 × 60 + 30
= 120 + 30
= 150 minutes
Put the value in above formula we get
N = N₀ [tex](\frac{1}{2})^{\frac{t}{t_{1/2}}[/tex]
N = 100 × [tex](\frac{1}{2})^{\frac{150}{30}}[/tex]
N = 100 × [tex](\frac{1}{2})^5[/tex]
N = 100 × [tex]\frac{1}{32}[/tex]
N = 3.125 grams
Thus, from above conclusion we can say that If an element has a half-life of 30 minutes, 3.125 gram of this element remains after 2 hours & 30 minutes if we start with 100 g of the element.
Learn more about the Half life here: https://brainly.com/question/25750315
#SPJ2
