Answer:
d. Radon-222
Explanation:
²²⁶₈₈Ra → ²²²₈₆Rn + ⁴₂He
Alpha particle is a helium nucleus with mass number 4 and atomic number 2. According to the law of conversation of mass, the sum of the mass number and atomic number must be equal on both side of the reaction.
Since the mass number of Ra is 226 and that of He is 4. The mass number of the unknown element must be 226 - 4 = 222.
Since the atomic number of Ra is 88 and that of He is 2. The atomic number of the unknown element must be 88 - 2 = 86.
Now looking in the periodic table Radon is the only element with atomic number 86.
There are various kind of elements that are present in periodic table. Some elements are harmful, some are radioactive, some are noble gases. The atomic radius in decreasing order is Bi>Sb>As>N>O.
<h3>
What is periodic table?</h3>
Periodic table is a table in which we find elements with properties like metals, non metals, metalloids and radioactive element arranges in increasing atomic number.
Along the period, the size of elements decreases. Down the group the size of elements increases. The atomic radius in decreasing order is Bi>Sb>As>N>O.
Therefore, atomic radius in decreasing order is Bi>Sb>As>N>O.
Learn more about periodic table, here:
brainly.com/question/11155928
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I think it's the c (<span>.all the gases that surround the Earth)</span>
I believe the correct response is A. At higher elevations it would take less time to hard boil an egg, because there is less atmospheric pressure.
