Answer:
Part 2:
There are 19 protons in the element K, you can tell because of the number 19 above the elements abbreviation. There are also 19 electrons in this element, you can tell because the number of protons is the same number of electrons. Last, to find the number of neutrons an atom possesses, you have to round the atomic mass ( 39.089 to 39 ). Then you take your Mass number ( 39 ) and subtract it from your number of protons (19). 39 - 19 = 29, there are 29 neutrons in the element K.
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Also if you need part 1 :)
Part 1:
The two-element that has the same properties as Magnesium are Calcium (Ca) and Strontium (Sr). These three elements are all Alkaline earth metals, they are not as reactive as Alkali metals but they are too reactive to be found in nature.