Question

What is the chemical formula of Potassium?
A.$K$
B.$Na$
C.$Ca$
D.$Cu$

Answer 1

Hint: We have to remember that the periodic table of elements is a structured arrangement of all the elements found in earth. The elements are arranged according to their properties and their nature as a metal or as a non-metal or both. These properties are called periodic properties. The elements on the left are metals and those on the right are non-metals.

Complete step by step answer:
We must have to know that the potassium is an element with an atomic number $19$ . It is a silvery white metal and an alkali metal. The symbol of potassium is $K$ derived from the Neo-Latin name Kalium. It is a soft metal which can be easily cut with a knife. In the periodic table it lies on group 1 and period 4.
We need to know that the $Na$ term is used to represent sodium with atomic number 11. Sodium is a metal lying in group 1 and period 3 of the periodic table. The symbol $Na$ is derived from Latin name Natrium. Just like potassium it can also be cut easily with a knife. But it is highly volatile in nature. Pure sodium in contact with oxygen can explode. Hence, they are not available in free state in nature. Therefore, the option B is incorrect.
We can also remember that the $Ca$ term is used for calcium. It is an alkaline earth metal with atomic number 20. It lies in group 1 and period 4 of the periodic table. Therefore, the option C is incorrect.
We must know that the $Cu$ term is used to represent copper. The symbol $Cu$ is derived from Latin name cuprum. It has an atomic number of 29 and it lies in group 11 and period 4 of the periodic table. Therefore, this option is incorrect.
Hence, the correct answer to the question is option A.

Note:
We must have to know that in periodic tables there are many elements which have a different name and they are represented by a different symbol. This is so because the symbols are given according to their Latin names. While a majority of elements are symbolized from their canonical name. Like Sodin is represented by Na (Natrium), Potassium is represented by K (Kalium), Gold is represented by Au (Aurum), Silver is represented by Ag (Argentum).