B. Hydrogen is the answer
Amount of Niobium-91 initially
= 300/91 =3.2967mol
2040 years = 3 ×680 = 3 half-lives
therefore, amount left = 0.4121mol
mass of Niobium-91 remaining = 0.4121 ×91 =37.5g
Answer:
C!
Explanation:
only C
A: solid B: liquid : C: GAS
Considering the ideal gas law, there are 279.42 moles of acetylene in the tank.
<h3>Definition of ideal gas</h3>
Ideal gases are a simplification of real gases that is done to study them more easily. It is considered to be formed by point particles, do not interact with each other and move randomly. It is also considered that the molecules of an ideal gas, in themselves, do not occupy any volume.
<h3>Ideal gas law</h3>
An ideal gas is characterized by three state variables: absolute pressure (P), volume (V), and absolute temperature (T). The relationship between them constitutes the ideal gas law, an equation that relates the three variables if the amount of substance, number of moles n, remains constant and where R is the molar constant of gases:
P×V = n×R×T
<h3>Moles of acetylene</h3>
In this case, you know:
- P= 1765 kPa= 17.4192 atm (being 101.325 kPa= 1 atm)
- V= 390 L
- n= ?
- R= 0.082

- T= 23.5 °C= 296.5 K (being 0 °C= 273 K)
Replacing in the ideal gas law:
17.4192 atm× 390 L = n×0.082
× 296.5 K
Solving:

<u><em>n= 279.42 moles</em></u>
Finally, there are 279.42 moles of acetylene in the tank.
Learn more about ideal gas law:
brainly.com/question/4147359
<u>Answer: </u><em>B. Adding more protons to a positively charged body until the number of protons matches the number of electrons</em>
Option B is the appropriate response
<u>Explanation:</u>
Utilising the equivalent number of inverse charges will kill a charged body.
Adding more protons to a decidedly charged body until the number of protons coordinates the quantity of electrons won't kill the body since protons are emphatically charged particles. Adding more protons to an emphatically charged body would make it all the more decidedly charged.
Enabling free electrons to escape from a contrarily charged body will kill since the more negative body leaves the negative electrons.