Download App

Structure of the Atom — Science STD 9 — Question

Rajasthan BoardEnglish MediumSTD 9ScienceStructure of the Atom2 Marks
Question
Why do helium, neon, and argon have zero valencies?
✓

Answer

Valency,the combining capacity of an element is equal to the no. of electrons needed to be removed from the outer most shell of the atom of the element, to have a complete ‘octet’.
He(2)
Electronic configuration : 2
Complete octet.
Ne(10)
Electronic configuration :2, 8
Complete octet.
Ar(18)
Electronic configuration : 2, 8, 8
Complete octet.
Since the octet is complete so there is no need to remove any electron. So the valency is 0.

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "Que-Ans (Each of 2 Mark )" from Structure of the Atom→Structure of the Atom — all question types→Science STD 9 question papers→Rajasthan Board STD 9 question papers→Rajasthan Board question paper generator→

Similar questions

The work done by a force acting obliquely is given by the formula: $\text{W} =\text{F}\cos\theta\times\text{s}.$ What will happen to the work done if angle between the direction of force and motion of the body is increased gradually? Will it increase, decrease or remain constant?
→
What is a chemical change?
Give two examples of chemical changes.
→
Name the elements water is made of. What are the valencies of these elements? Work out the chemical formula for water.
→
Why is it difficult to hold a school bag having a strap made of a thin and strong string?
→
What is a suspension? Give two examples of suspensions.
→
Which one of the following crops require a minimum quantity of NPK or urea for its proper growth paddy, peas, wheat, sugarcane.
→
What types of functions does the single cell of unicellular organisms such as Amoeba perform?
→
Write the cations and anions present $($if any$)$ in the following compounds.
$a.CH_3COONa \ \ \ b.NaCI \ \ \ c.H_2 \ \ \  d.NH_4N0_3$
→
A certain household consumes $650$ units of electricity in a month. How much is this electricity in joules?
→
Two children are at opposite ends of an aluminium rod. One strikes the end of the rod with a stone. Find the ratio of times taken by the sound wave in air and in aluminium to reach the second child.
→