Write true or false for the statement: Electronic configuration of hydrogen resembles that of alkaline earth metals.

Two elements $P$ and $Q$ belong to the same period of the modern periodic table and are in Group $1$ and Group $2$ respectively. Compare their following characteristics in tabular form:
$(a)$ The number of electrons in their atoms
$(b)$ The sizes of their atoms
$(c)$ Their metallic characters
$(d)$ Their tendencies to lose electrons
$(e)$ The formula of their oxides
$(f)$ The formula of their chlorides

In Mendeleev's Periodic Table,gaps were left for elements to be discovered later. Which of the following elements found a place in the periodic table later?

Elements have been arranged in the following sequence on the basis of their increasing atomic masses.
$F, Na, Mg, Al, Si, P, S, Cl, Ar, K$
$(a)$ Pick two sets of elements which have similar properties.
$(b)$ The given sequence represents which law of classification of elements?

An element $X$ of group $15$ exists as a diatomic molecule and combines with hydrogen at $773 \, K$ in the presence of a catalyst to form a compound,ammonia,which has a characteristic pungent smell.
$(a)$ Identify the element $X$. How many valence electrons does it have?
$(b)$ Draw the electron dot structure of the diatomic molecule of $X$. What type of bond is formed in it?
$(c)$ Draw the electron dot structure for ammonia and what type of bond is formed in it?

What is the position of metalloids in the periodic table?