TEST YOURSELF 2.3 Chemistry 9th Chapter 2

Test yourself 2.3

(1) How many the maximum number of electrons that can be accommodated in a p subshell?

 Ans. Maximum number of electrons that can be accommodated in a p-subshell is six (6).

(2) How many subshells are there in second shell?

Ans. second shell has two subshells i.e. s and p .

(3) Why does an electron first fill 2p orbital and then 3s orbital?

Ans. Electrons are accommodated in different shells according to increasing energy.

An electron first fill 2p orbital and then 3s orbital because 2p orbital is lower in energy than 3s orbital

(4) If both K and L shells of an atom are completely filled; how many total number of electrons are present in them?

Ans. If both K and L shells of an atom are completely filled then there are 10 total electrons present in them.

(5) How many electrons can be accommodated in M shell?

Ans. 2n formula tells us that M shell can accommodate 18 electrons in it.

(6) What is the electronic configuration of a hydrogen atom?

Ans. The electronic configuration of a hydrogen atom is 1s¹.

(7) What is atomic number of phosphorus? Write down its electronic configuration?

Ans. Atomic number of phosphorus is 15. Its electronic configuration is 1s²,2s²,2p⁶,3s²,3p³ .

(8) If an element has atomic number 13 and atomic mass 27; how many electrons are there in each atom of the element?

 Ans. The number of electrons present is this atom is also 13.

(9) How many electrons will be in M shell of an atom having atomic number 15.

Ans. Electronic configuration of an element having atomic number 15 is:

• K shell = 2, L shell = 8, M shell = 5

             There are 5 electrons in M shell.

(10) What is maximum capacity of a shell?

Ans. Maximum capacity of a shell is found by 2n² formula .