Answer:
52 da
Step-by-step explanation:
Whenever a question asks you, "How long to reach a certain concentration?" or something similar, you must use the appropriate integrated rate law expression.
The i<em>ntegrated rate law for a first-order reaction </em>is
ln([A₀]/[A] ) = kt
Data:
[A]₀ = 750 mg
[A] = 68 mg
t_ ½ = 15 da
Step 1. Calculate the value of the rate constant.
t_½ = ln2/k Multiply each side by k
kt_½ = ln2 Divide each side by t_½
k = ln2/t_½
= ln2/15
= 0.0462 da⁻¹
Step 2. Calculate the time
ln(750/68) = 0.0462t
ln11.0 = 0.0462t
2.40 = 0.0462t Divide each side by 0.0462
t = 52 da
Answer:
<u>Yes</u>
Explanation:
Remember, <u>Newton's third law of motion;</u> which says in part that <em>"Every action has an equal and opposite reaction."</em>
Hence, in this case, the fact that the doorbell rang out implies that there was another force that was exerted on it; which is, John's finger pressing the doorbell.
In other words, when John uses his fingers to press the doorbell button he applies a force (a mechanical force), and that force results in an opposite reaction; the ringing of the doorbell.
Hello there!
To determine the fraction of the hydrogen atom's mass that is in the nucleus, we have to keep in mind that
a Hydrogen atom has 1 proton and 1 electron.
Protons are in the nucleus while electrons are in electron shells surrounding the nucleus.
The mass of the nucleus will be equal to the mass of 1 proton and we can express the fraction as follows:

So, the fraction of the hydrogen atom's mass that is in the nucleus is
0,9995. That means that almost all the mass of this atom is at the nucleus.
Have a nice day!
<span>The answer is B.They cannot produce enough heat to keep their bodies warm.
In order to survive, the alligators rely on warm weather, and they are most active when the environment is 82-92 degrees Fahrenheit. They can survive below or above this temperature range but they may spend that time struggling to stay warm or stay cool.
</span>
True because certain fabric will catch on fire