The horizontal rows in a periodic table are called .

In going across a period (right to left) in periodic table, the atomic size of the atom _____.

On moving from right to left in the second period, the number of valence electrons _____.

On going down in a group in the periodic table, the metallic character of elements _____.

The tendency to gain an electron _____ on moving down in a group of the periodic table.

Nitrogen (Atomic number $7$) and phosphorus (atomic number $15$) belongs to group $15$ of the periodic table. Write the electronic configurations of these two elements. Which of these will be more electronegative? Why?

An element $\mathrm{X}$ belongs to group $2$ and another element $\mathrm{Y}$ belongs to group $15$ of the periodic table. What is the number of valence electron in $\mathrm{X}$? Explain how you have arrived at your answers.

An element $\mathrm{X}$ belongs to group $2$ and another element $\mathrm{Y}$ belongs to group $15$ of the periodic table. What is the valency of $\mathrm{X}$? Explain how you have arrived at your answers.

An element $\mathrm{X}$ belongs to group $2$ and another element $\mathrm{Y}$ belongs to group $15$ of the periodic table. What is the number of valence electron in $\mathrm{Y}$? Explain how you have arrived at your answers.