Answer:
All the members of a group of elements have the same number of valence electrons and similar chemical properties.
Explanation:
The vertical columns on the periodic table are called groups or families because of their similar chemical behavior.
The equation for carbon-14 emission by Radium-223 nuclei is given below:

<h3>What is radioactivity?</h3>
Radioactivity is the spontaneous decay of a substance with emission of radiation.
The equation for carbon-14 emission by Radium-223 nuclei is given below:

In conclusion, the emission of carbon-14 by Radium-223 nuclei produces Lead-209 nuclei.
Learn more about radioactivity at: brainly.com/question/3603596
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CaCO3 + 2KCL ⇒ CaCl2 + K2CO3
It is balanced as so based on the charges given on the periodic table and polyatomic ions.
Calcium has the charge of 2 but CO3 also shares the same charge, thus cancelling that out.
Potassium has a charge of 1 while Chlorine also shares a charge of 1, also cancelling it out.
Thus, if it performs a double replacement reaction, they would take these charges to the new elements that do not cancel out their charges.
Therefore, we need the coefficient of 2 in front of Potassium Chloride in order to balance the equation as on the products side of the equation, Potassium and Chlorine both have a subscript of 2.
Hope this helps!