Question

Three elements P, Q and R with their atomic number are given –

P (Z = 11) , Q( Z= 15) , R( Z = 18)

Choose the correct match-

Elements Specification

P i) Noble gas

Q ii) Cut with knife

R iii) Has valency 3

a) P- (i), Q - (iii), R - (ii)

b) P- (ii), Q - (iii), R - (i)

c) P - (iii), Q -(i), R - (ii)

d) P - (ii), Q - (i), R - (iii)​

Answer 1

Correct Question :-

Three elements P, Q and R with their atomic number are given – P (Z = 11) , Q( Z= 15) , R( Z = 18)

Choose the correct match - Elements Specification

• P i) Noble gas
• Q ii) Cut with knife R
• R iii) Has valency 5

a] P- (i), Q - (iii), R - (ii)

b] P- (ii), Q - (iii), R - (i)

c] P - (iii), Q -(i), R - (ii)

d] P - (ii), Q - (i), R - (iii)

Required Answer :-

Given Atomic number of P = 11

Then , the electronic configuration of "P" is;

• 1s² 2s² 2p⁶ 3s¹

Observing the configuration of "P" ;

• Valency of "P" is 1 {Since number of valence electrons is 1}
• Element with atomic number 11 is sodium. Sodium is an alkali metal. It is soft and can be cut with a knife.

Given atomic number of "Q" = 15

Then , the electronic configuration of "Q" is;

• 1s² 2s² 2p⁶ 3s² 3p³

Observing the configuration of "Q" ;

• Valency of "Q" is 5 { Since Total number of valence electrons are 5}
• Element with atomic number 15 is phosphurus (a non-metal). Phosphorus is not a noble gas and cannot be cut with a knife.

Given atomic number of "R" = 18

The Electronic configuration of "R" is ;

• 1s² 2s² 2p⁶ 3s² 3p⁶

Observing the configuration of "R" ;

• Valency of "R" is 8. {Since total number of valence electrons is 8}
• Element with atomic number 18 is argon . Argon is a noble gas

Now , The suitable matches for "P" , "Q" and "R" are ;

• P - (ii) , Q - (iii) , R - (i)

Observing the options , Option(b) contains the correct match.

Hence , Option(b) is the required answer.

Answer 2

$\Large\bf{\color{indigo}GiVeN,}$

• Atomic no. of P is 11.

• Atomic no. of Q is 15.

• Atomic no. of Z is 18.

$\Large\bf{\color{cyan}DiScUsSiOn,}$

ATOMIC No. 11 ;-

• Sodium is the element whose At. no. is 11.

☆ Sodium is reactive, soft metal with a low melting point and most important of all the alkaline metals from the commercial point of view.

☆ Sodium is a soft metal, that's why it can be cut easily with a table knife.

ATOMIC No. 15 ;-

• Phosphorus is the element whose At. no. is 16.

☆ We know that, like one atom of phosphorus combines with three atoms of hydrogen to form the normal hydride phosphene, $\bf{PH_3}$. Therefore, the valency of phosphorus is 3.

ATOMIC No. 18 ;-

• Argon is the element whose At. no. is 18.

☆ As we know that group-18 elements are known as noble gases, that's why Argon is a noble gas element.

$\Large\bf{\color{red}MaTcHiNg,}$

● From the above discussions we have,

$:\implies\:\:\bf\purple{P\:\longrightarrow\:\longrightarrow\:(ii)\:Cut\:with\:knife\:}$

$:\implies\:\:\bf\orange{Q\:\longrightarrow\:\longrightarrow\:(iii)\:Has\:valency\:3\:}$

$:\implies\:\:\bf\green{R\:\longrightarrow\:\longrightarrow\:(i)\:Noble\:gas\:}$

$\red\bigstar\:\:{\boxed{\boxed{\bf{\pink{Correct\:Option\:\longrightarrow\:(b)\:}}}}}$