The Periodic Table Exe-5C Short Answer Chemistry Class-9 ICSE Selina Publishers Solutions Chapter-5. Step By Step ICSE Selina Concise Solutions of Chapter-5 The Periodic Table with All Exercise including MCQs, Very Short Answer Type, Short Answer Type, Long Answer Type, Numerical and Structured/Application Questions Solved . Visit official Website CISCE for detail information about ICSE Board Class-9.
The Periodic Table Exe-5C Short Answer Chemistry Class-9 ICSE Concise Selina Publishers
| Board | ICSE |
| Publications | Selina Publication |
| Subject | Chemistry |
| Class | 9th |
| Chapter-5 | The Periodic Table |
| Book Name | Concise |
| Topics | Solution of Exercise – 5C Short Answer type |
| Academic Session | 2023-2024 |
Exercise – 5C Short Answer type
The Periodic Table Class-9 Chemistry Concise Solutions
Page-100
Question 1.
Arrange the following:
(a) Elements of group 1, in increasing order of reactivity.
(b) Elements of group 17, in decreasing order of reactivity.
(c) He, Na, Mg (decreasing order of valency).
(d) Chlorine, sodium, magnesium (increasing reducing character).
Answer:
(a) Li < Na < K < Rb < Cs
(b) F > Cl > Br > I
(c) Mg > Na > He
(d) Cl < Mg < Na
Question 2.
Element P has atomic number 19. To which group and period, does P belong? Is it a metal or a non-metal? Why?
Answer:
Atomic number of P = 19
Its electronic configuration = 2, 8, 8, 1
Group no. of the element = 1A
Period no. of the element = 4
P is a metal.
Question 3.
An element belongs to the third period and Group IIIA (13) of the periodic table. State:
(a) the number of valence electrons,
(b) the valency,
(c) if it is a metal or non-metal?
(d) the name of the element.
Answer:
(a) 3, as the electronic configuration of the element is 2,8,3.
(b) +3, as the element will try to donate three valence electrons and attain a stable octet configuration.
(c) Metal, as the element has 3 valence electrons and tries to donate it to attain a stable configuration.
(d) Aluminium (Al), as it is in 3rd period and Group IIIA (13)
Question 4.
An element A has 2 electrons in its fourth shell. State:
(a) its atomic number
(b) its electronic configuration
(c) its valency
(d) position in the periodic table
(e) is it a metal or a non-metal?
(f) is it an oxidising or reducing agent?
Answer:
(a) Atomic number is 20.
(b) Its electronic configuration is 2, 8, 8, 2.
(c) +2, as the element tries to donate the two valence electrons, gain a stable octet configuration and become an electropositive ion.
(d) Group 2 Period 4
(e) Metal, as the element has 2 valence electrons and tries to donate it to attain a stable configuration.
(f) Reducing agent, as metals are strong reducing agents.
Question 5.
(a) Name the first three alkaline earth metals.
(b) Write the reactions of first three alkaline earth metals with dilute hydrochloric acid.
Answer :
(a) The first three alkaline earth metals are Beryllium, Magnesium and Calcium.
(b) Reactions of the first three alkaline earth metals with dilute hydrochloric acid:
Be + 2HCl → BeCl2 + H2
Mg + 2HCl → MgCl2 + H2
Ca + 2HCl → CaCl2 + H2
Question 6.
(a) Name the alkali metals, How many electron(s) they have in their outermost orbit.
(b) Take any one alkali metal and write its reaction with (i)oxygen (ii)water (iii)acid.
Answer:
(a) Name of the alkali metals: Lithium, sodium, potassium, rubidium, cesium and francium electrons in the outermost orbit:
(b) Reaction of alkali metal with oxygen – React rapidly with oxygen. 4Na + O2 → 2Na2O
Reaction of alkali metal with water – React with water violently and produce hydrogen. 2M + 2H2O → 2MOH + H2
Reaction of alkali metal with acid – React violently with dil. HCl and dil. H2SO4to produce hydrogen
2M + 2HCl → 2MCl + H2
Question 7.
(a) How do alkaline earth metals occur in nature?
(b) Write the electronic configuration of the first two alkaline earth metals.
Answer:
(a) Alkaline earth metals occur in nature in the combined state and not in the free state as they are very reactive.
(b) Electronic configuration of the first two alkaline earth metals:
4Be: 1s22s2
12Mg: 1s22s22p63s2
Question 8.
(a) How many electrons do inert gases have in their valence shells?
(b) Name an element of group 18 which can form compounds.
Answer:
(a) All the noble or inert gases have 8 electrons in their valence shell except helium which has two electrons in its valence shell.
(b) Xenon or krypton from Group 18 can form compounds.
Exercise – 5C Short Answer type
The Periodic Table Class-9 Chemistry Concise Solutions
Page-101
Question 9.
Give reasons:
Give reasons.
(a) Alkali metals are kept in inert solvent.
(b) Alkali metals and halogens do not occur free in nature.
(c) Alkali and alkaline earth metal compounds usually form electrovalent compounds.
(d) Inert gases do not form compounds.
Answer:
(a) As alkali metals are very reactive metals, hence they are kept in inert solvents.
(b) As alkali metals and halogens are very reactive, hence, they do not occur free in nature.
(c) As alkali and alkaline earth metal have 1 and 2 valence electrons respectively hence, they tend to donate the valence electrons to attain a stable configuration and form electrovalent compounds.
(d) As the outermost orbits of inert gases are completely filled and they are in a stable state hence they do not form compounds.
— : End of The Periodic Table Exe-5C Short Answer Class-9 ICSE Chemistry Solutions :–
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