Answer: Option (c) is the correct answer.
Explanation:
Atomic number of sodium is 11 and its electronic configuration is 
. When sodium loses one electron then it will attain +1 charge and its electronic configuration will be as follows.
: 
Atomic number of fluorine is 9 and its electronic configuration is 
. When fluorine gains an electron then it acquires -1 charge and its electronic configuration is as follows.
:
Atomic number of aluminium is 13 and its electronic configuration is 
. When aluminium loses its valence electrons then it acquires +3 charge and its electronic configuration is as follows.
:
Thus, we can conclude that the listing for aluminum is correct.
<u>Answer:</u> The element having similar chemical properties that of calcium present in period 3 is magnesium.
<u>Explanation:</u>
In a periodic table, elements are arranged in 18 vertical columns known as groups and 7 horizontal rows known as periods.
Elements arranged in a group show similar chemical properties because of the presence of same number of valence electrons.
We are given:
Calcium is the 20th element of the periodic table having electronic configuration 
It has 2 valence electrons.
The element present in period 3 and have the same number of valence electron or in the same group is magnesium.
Hence, the element having similar chemical properties that of calcium present in period 3 is magnesium.
Answer:
Atomic number 29
Atomic mass 63.546 g.mol -1
Electronegativity according to Pauling 1.9
Density 8.9 g.cm-3 at 20°C
Melting point 1083 °C
