Radium-226 is a radioactive element, and its decay rate is modeled by the equation r = r0e-0.000428t. how many years will it take for 100 grams of radium-226 to reduce to half its mass? 810 1,620 2,690 5,380

1620 years

Step-by-step explanation:

Given : Radium-226 is a radioactive element, and its decay rate is modeled by the equation R = R0e-0.000428t

Solution:

We will find total number of particles in 100 gram sample :

    Ro = 100 grams * 1 mol / 226 g = 0.4425 mol

Now we will find total number of particles when the 100 gram sample is reduced to half its mass:

    R = Ro/2 = 0.4425/2 = 0.2212

On substituting values of Ro and R to the decay rate equation, we get

    R = Ro e^-0.000428t

     0.2212   = 0.4425 e^-0.000428t

        = e^-0.000428t

Now, take natural logarithm on both sides of the equation in order to find value of t .

    ln (0.2212/0.4425) = -0.000428t

    t= ln (0.2212/0.4425) / (-0.000428)

    t = 1620 years

nswer: a   y-axis

step-by-step explanation:

step-by-step explanation:

because 1/3 is a fraction. we can tell because there is a divisor symbol between the 1 and the 3. if we were to add 2 fractions together, we would add the numerators, which is the number on top, but not the denominators, which is the number on the bottom

1/3+1/3=2/3

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