Answer:
Explanation:
Isotopes are atoms of elements that have the same atomic number but different mass number hence ISOTOPY. Radioactive Isotopes on the other hand are unstable as they either undergo Alpha decay, beta decay or gamma decay compared to stable isotopes.
Radioactive elements decay at varyinf rates as such the rate of radioactive decay is used in the characterization of radioactive element and mostly expressed in terms of the half life of the radioactive elements.
Half life is the time taken for half of the total atoms of an elements to decay into half of its initial sizes. for example, the half life of radium-226 is 1622 years, it implies that if we have 1000000 radium atoms at the beginning, then at the end of 1622years, 500000 would have disintegrated. These phenomenon can never be experienced by stable isotopes as such they can not be used in carbon dating techniques. reason why uranium-238 is mostly and commonly used in the earth crust to estimate the ages of rocks because it has a half life of 4.5 x 10^9 years.
And also, the radioactive isotopes of most common light element are short, they have very short half life (few days or weeks) and they decay rapidly to vanshing point, as such, they are not found in nature to any reasonable extent.
Is this a multiple choice? Anyways I will just give you a written answer and hopefully it helps.
A: Helium is made up of two electrons held by electromagnetic force to two protons that are inside of a nucleus along with one or two neutrons.
We can define atomic mass the total of number of protons and number of neutrons in an atom or isotope.
<span>So when an isotope of yttrium has 39 protons and 59 neutrons, its atomic mass is equal to;
number of protons + number of neutrons = 39 + 59 = 98</span>
Answer:
You need 8,324 g of CaCl₂ yo make this solution
Explanation:
Molarity is a way to express concentration in a solution, in units of moles of solute per liter of solution.
To know the grams of CaCl₂ it is necessary to know, first, the moles of this substance with the desired volume and concentration , thus:
0,1500 L × 
= 0,075 CaCl₂ moles
Now, with the molar mass of CaCl₂ you will obtain the necessary grams, thus:
0,075 CaCl₂ moles × 
= 8,324 g of CaCl₂
So, you need <em>8,324 g of CaCl₂</em> to make 150,0 mL of a 0,500M solution
I hope it helps!
