Answer:
Is this chemistry or ELA!
Answer:
Taking into account the definition of average atomic mass and isotopes of an element, the information that you need is the masses of its isotopes and their percent abundances.
Each chemical element is characterized by the number of protons in its nucleus, which is called the atomic number Z.
But in the nucleus of each element it is also possible to find neutrons, whose number can vary. The atomic mass (A) is obtained by adding the number of protons and neutrons in a given nucleus.
The same chemical element can be made up of different atoms, that is, their atomic numbers are the same, but the number of neutrons is different. These atoms are called isotopes of the element.
The atomic mass of an element is the weighted average mass of its natural isotopes. Therefore, the atomic mass of an element is not a whole number.
The weighted average means that not all isotopes have the same percentage.
In other words, the atomic masses of chemical elements are usually calculated as the weighted average of the masses of the different isotopes of each element, taking into account the relative abundance of each of them.
Explanation:
C, it prevents the Earth from ultraviolet radiation and other harmful substances from space
The radioactive decay obeys first order kinetics
the rate law expression for radioactive decay is
![ln\frac{[A_{0}]}{[A_{t}]}=kt](https://tex.z-dn.net/?f=ln%5Cfrac%7B%5BA_%7B0%7D%5D%7D%7B%5BA_%7Bt%7D%5D%7D%3Dkt)
Where
A0 = initial concentration
At = concentration after time "t"
t = time
k = rate constant
For first order reaction the relation between rate constant and half life is:
Let us calculate k
k = 0.693 / 72 = 0.009625 years⁻¹
Given
At = 0.25 A0
time = 144 years
So after 144 years the sample contains 25% parent isotope and 75% daughter isotopes**
Simply two half lives
Answer is: the missing pressure is 1088.66 mmHg.
Gay-Lussac's Law states that the pressure of a given amount of gas held at constant volume is directly proportional to the Kelvin temperature.
p₁/T₁ = p₂/T₂.
p₁ = 960 mmHg; pressure of the gas.
T₁ = 100°C + 273.15.
T₁ = 373.15 K; temperature of the gas.
T₂ = 150°C + 273.15.
T₂ = 423.15 K.
p₂ = p₁T₂/T₁.
p₂ = 960 mmHg · 423.15 K / 373.15 K.
p₂ = 1088.66 mmHg.
