Question

Statement (A): In periodic table, the horizontal rows are called periods.
Statement (B) : In periodic table Vertical columns are called groups.
Statement (C): Atomic number of Calcium is 20
a) All the above statements are correct
b) All the above statements are incorrect
c) A and B are correct but C is incorrect
d) A and B are incorrect but C is correct​

Answer 1

✔️$\large\mathcal \red \bigstar{\underline{\purple{Periods}}}:-$

Periods are the 7 horizontal rows in which number of velence electron first increased one-by-one then decreased gradually.

Example of Periods:-

Period 1 contains only two elements:-

Hydrogen. Helium

_______________________________

✔️$\large\mathcal \red \bigstar{\underline{\blue{GROUP}}}:-$

Groups are the 18 vertical columns in which no.of valence Electrons remain same.The elements of same group show same chemical properties or regular increasement or decreament in Physical or chemical properties.

Example:-

Group 1 contains alkali elements whose no. of velence electron is 1

H

Li

Na

K

Rb

Cs

Fr

_________________________________

✔️$\large\mathcal \red \bigstar{\underline{\orange{Calcium}}}:-$

Calcium belongs to 2nd group and period no. 4

therefore...

it's Electron Configuration be like

$(ar)4 {s}^{2}$

It come after K in table whose Atomic number be 19.

Remember this:-

In a period no. of velence electron first increased one-by-one then decreased gradually.

Ca=k +1

Ca=19+1

Atomic number=20

Atomic number=No.of Protons

___________________________________

Hence,

All are correct statement.

THEREFORE Option a) is correct ✔️

Answer 2

Answer:

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