Answer:
Explanation:
Lithium, Potassium and Sodium follow each other in that order when it comes to reactivity.
Succinctly put, Lithium is the most reactive. Potassium is more reactive and Sodium is the least reactive.
Also, for Calcium, Strontium and Barium. It is the least reactive in this order.
Strontium, Barium, Calcium
That is, Strontium is more reactive than Barium, which is more reactive than Calcium. Calcium is the least reactive of the 3
The answer is 1/8.
Half-life is the time required for the amount of a sample to half its value.
To calculate this, we will use the following formulas:
1.

,
where:
<span>n - a number of half-lives
</span>x - a remained fraction of a sample
2.

where:
<span>

- half-life
</span>t - <span>total time elapsed
</span><span>n - a number of half-lives
</span>
The half-life of Sr-90 is 28.8 years.
So, we know:
t = 87.3 years
<span>

= 28.8 years
We need:
n = ?
x = ?
</span>
We could first use the second equation, to calculate n:
<span>If:

,
</span>Then:

⇒

⇒

<span>⇒ n ≈ 3
</span>
Now we can use the first equation to calculate the remained amount of the sample.
<span>

</span>⇒

⇒

<span>
</span>
When the object has something added to it
Answer:
The correct answer is option B) "Higher-magnitude earthquakes do not always happen deeper in Earth's crust".
Explanation:
The table shows data of magnitude and depth of earthquakes that occurred at different time and at different locations. By analyzing the data we can conclude that higher-magnitude earthquakes do not always happen deeper in Earth's crust. At first glance we can thought that higher-magnitude earthquakes occur at high depth. However, the earthquake of Michoacan have a higher-magnitude than the earthquake of Alexandria (8 and 6.3, respectively), and the earthquake of Michoacan occurred at 12 miles of depth, while the earthquake of Alexandria occurred at 15 miles of depth.