<span>Because iron is an element meaning that it only contains iron atoms, pure iron is easily oxidized meaning that oxygen readily reacts with the surface of the iron which causes it to rust. Therefore, since the iron joint replacement is surrounded by wet tissues would it would rust and flake off which could cause serious problems. </span>
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>
What statement?
Light moves faster through a vacuum because no particles are existent to absorb it.
Answer:
it's SN1 reaction,
it's takin double step to complete,first formation of carbocation and then attack of reagents,so it's SN1!