A DC motor requires a magnetic force to create its rotational power
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Hi!
The generic equation showing how a weak base ionizes water is the following:
B(aq) + H₂O(l) ⇄ BH⁺(aq) + OH⁻(aq)
A base is described as weak when its dissociation is difficult and isn't complete. Weak Bases are chemical compounds that accept protons from water, to form the conjugate acid and the OH⁻ ion. The pH of the solution of a weak base is higher than 7. Some weak bases include ammonia (NH₃), Aluminum Hydroxide (Al(OH)₃) and Sodium Acetate (CH₃COONa).
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Depending on the size of the object, that system may describe it
in terms of inches, feet, yards, chains, rods, or miles.
The answer is 3.75 g.
Half-life is the time required for the amount of a sample to half its value.
To calculate the fraction of the sample remained unchanged, 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 N-16 is 7.13.
So, we know:
t = 28.8 s
<span>

= 7.13 s
We need:
n = ?
x = ?
</span>
We could first use the second equation, to calculate n:
<span>If:

,
</span>Then:

⇒

⇒

<span>⇒ n ≈ 4
</span>
Now we can use the first equation to calculate the remained amount of the sample.
<span>

</span>⇒

<span>⇒

If the fraction of the sample is 1/16 = 6.25%, then the mass of the sample could be calculated as:
x g : 6.25% = 60 g : 100%
x = </span>