Answer:
23 years
Step-by-step explanation:
Step 1: Calculate the rate constant (k) for the radioactive decay
A radioactive substance with initial concentration [A]₀ decays to 97% of its initial amount, that is, [A] = 0.97 [A]₀, after t = 1 year. Considering first-order kinetics, we can calculate the rate constant using the following expression.
ln [A]/[A]₀ = - k.t
k = ln [A]/[A]₀ / -t
k = ln 0.97 [A]₀/[A]₀ / -1 year
k = 0.03 year⁻¹
Step 2: Calculate the half-life of the substance
We will use the following expression.
= ln2/ k = ln 2 / 0.03 year⁻¹ = 23 years
Answer:
1 1/2 teaspoon of salt is required
Step-by-step explanation:
The recipe requires 3/4 cup of flour and Nick wants to make the recipe using 1 cup of flour.
The recipe requires 1 1/8 teaspoon of salt and Nick wants to know how much salt he heeds.
Consider short description:
3/4 cup of flour - 1 cup of flour,
1 1/8 teaspoon of salt - x teaspoon of salt.
Mathematically, you can wrte a proportion:
<u>3/4 </u> = 1 / x
<u>1 1/8 </u>
Then
3/4 * x = 1 x 1 1/8,
3x/4 = 9/8,
3x x 8 = 4 x 9,
24x = 36,
x = 36/24 = 3/2 = 1 1/2