Question

question 8 (multiple choice worth 2 points) tg.02the table below compares the radioactive decay rates of two materials. material original mass of material (in grams) mass of material after 21.6 seconds (in grams) 1 100 12.5 2 200 25 based on the table, which of these conclusions is most likely correct? the half - life of material 1 and material 2 are equal. the half - life of material 2 is double the half - life of material 1. the half - life of material 2 is 10.8 seconds more than the half - life of material 1. the half - life of material 1 is 10.8 seconds more than the half - life of material 2. question 9 (multiple choice worth 2 points) tg.03which of these plate tectonic features occurs when earth plates move away from each other? transform boundaries convergent boundaries divergent boundaries convection boundaries

Explanation:

Question 8

Step1: Calculate decay factor for Material 1

The original mass of Material 1 is 100 grams and it decays to 12.5 grams in 21.6 seconds. Let $n_1$ be the number of half - lives. We know that $N = N_0\times(\frac{1}{2})^n$. So, $12.5=100\times(\frac{1}{2})^{n_1}$, then $(\frac{1}{2})^{n_1}=\frac{12.5}{100} = 0.125$, and $n_1 = 3$. Since it occurs in 21.6 seconds, the half - life of Material 1, $t_{1/2,1}=\frac{21.6}{3}=7.2$ seconds.

Step2: Calculate decay factor for Material 2

The original mass of Material 2 is 200 grams and it decays to 25 grams in 21.6 seconds. Let $n_2$ be the number of half - lives. Using $N = N_0\times(\frac{1}{2})^n$, we have $25 = 200\times(\frac{1}{2})^{n_2}$, then $(\frac{1}{2})^{n_2}=\frac{25}{200}=0.125$, and $n_2 = 3$. Since it occurs in 21.6 seconds, the half - life of Material 2, $t_{1/2,2}=\frac{21.6}{3}=7.2$ seconds.

When Earth plates move away from each other, the plate tectonic feature that occurs is divergent boundaries. Transform boundaries are where plates slide past each other, convergent boundaries are where plates move towards each other, and convection is a process within the Earth's mantle, not a type of plate boundary.

Answer:

The half - life of Material 1 and Material 2 are equal.

Question 9