Its easy...
Consider C as Potassium (K) atm no.-19
so a+2=19 so a=17
so A is halogen B is noble gas and C is Alkali metal
and between alkali metals and halogen their exist ionic bond
Example-KCl

In order to determine the nature of bonding in compounds A and C, we need to analyze the atomic numbers of the elements involved. Let's break down the information provided:

- Atomic number of element A: a
- Atomic number of element B: a + 1
- Atomic number of element C: a + 2

Now, let's assess the nature of bonding in compounds A and C separately.



Since the atomic number of element A is a, we can refer to the periodic table to identify the element corresponding to this atomic number. The periodic table organizes elements in order of increasing atomic number, so we can determine the element based on the value of a.

Once we identify element A, we can assess its bonding nature based on its position in the periodic table. Elements can be broadly categorized into metals, nonmetals, and metalloids.

- Metals: Elements located on the left side and the middle of the periodic table are generally metals.
- Nonmetals: Elements located on the right side of the periodic table, including the halogens and the noble gases, are nonmetals.
- Metalloids: Elements located along the "staircase" line between metals and nonmetals are metalloids.

Depending on the position of element A, we can determine its bonding nature:

- If element A is a metal, the bonding in compound A is likely to be ionic or metallic.
- If element A is a nonmetal, the bonding in compound A is likely to be covalent.
- If element A is a metalloid, the bonding in compound A could exhibit characteristics of both ionic and covalent bonding.



We are given that element C is an alkali metal. Alkali metals are a group of elements located in Group 1 of the periodic table, including lithium (Li), sodium (Na), potassium (K), and so on. These elements have a +1 charge when they form ions.

Based on this information, we can infer that the bonding in compound C is predominantly ionic. Alkali metals readily lose their outermost electron to achieve a stable electron configuration, forming a cation with a +1 charge. This cationic behavior suggests that the alkali metal (element C) will readily bond with an anion to form an ionic compound.

Ionic bonding occurs when there is a transfer of electrons from a metal to a nonmetal. The electrostatic attraction between the positively charged metal cation and the negatively charged nonmetal anion creates the ionic bond.

Therefore, in compound C, the bonding nature is primarily ionic due to the alkali metal behavior of element C.

To summarize:
- In compound A, the bonding nature depends on the position of element A in the periodic table, which can be a metal, nonmetal, or metalloid.
- In compound C, the bonding nature is predominantly ionic, driven by the alkali metal behavior of element C.