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Lakhmir Singh solutions for Class 9 Science chapter 4 - Structure of the Atom

Class 9 Chemistry - Science Part 2

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Lakhmir Singh Class 9 Chemistry - Science Part 2

Class 9 Chemistry - Science Part 2 - Shaalaa.com

Chapter 4: Structure of the Atom

Very Short Answer Type QuestionsShort Answer Type QuestionsLong Answer type QuestionsMultiple Choice QuestionsQuestion Based on High order Thinking skills ( Hot Questions)Long Answer Type QuestionsMultiple Choice Questions( MCQs)Questions Based On High Order Thinking Skills (HOTS)

Chapter 4: Structure of the Atom Exercise Very Short Answer Type Questions, Short Answer Type Questions, Long Answer type Questions, Multiple Choice Questions, Question Based on High order Thinking skills ( Hot Questions) solutions [Pages 191 - 195]

Very Short Answer Type Questions | Q 1 | Page 191

Which subatomic particle is not present in an ordinary hydrogen atom?

Very Short Answer Type Questions | Q 2 | Page 191

Name the scientists who described the arrangement of electrons in an atom.

Very Short Answer Type Questions | Q 3 | Page 191

What is the maximum number of electrons which can be accommodated in the K shell of an atom?

Very Short Answer Type Questions | Q 4 | Page 191

What is the maximum number of electrons which can be accommodated in the L shell of an atom?

Very Short Answer Type Questions | Q 5 | Page 191

What is the maximum number of electrons an M shell of the atom can accommodate?

Very Short Answer Type Questions | Q 6 | Page 191

What is the maximum number of electrons that can go into the N shell of an atom?

Very Short Answer Type Questions | Q 7 | Page 191

What is the maximum number of electrons which can be accommodated in the :
(a) innermost shell of an atom?
(b) outermost shell of an atom?

Very Short Answer Type Questions | Q 8 | Page 191

Name the three subatomic particles present in an atom.

Very Short Answer Type Questions | Q 9 | Page 191

Name the negatively charged particle present in the atoms of all the elements.

Very Short Answer Type Questions | Q 10 | Page 191

Name the scientist who discovered electron.

Very Short Answer Type Questions | Q 11 | Page 191

What is the usual symbol for (a) and electron (b) a proton, and (c) a neutron?

Very Short Answer Type Questions | Q 12.1 | Page 192

State whether the following statement is true or false :
Thomson proposed that the nucleus of an atom contains protons and neutrons.

  • True

  • False

Very Short Answer Type Questions | Q 12.2 | Page 192

State whether the following statement is true or false :
The cathode rays obtained from all the gases consist of negatively charged particles called electrons.

  • True 

  • False

Very Short Answer Type Questions | Q 12.3 | Page 192

State whether the following statement is true or false :
The anode rays obtained from all the gases consist of positively charged particles called protons.

  • True

  • False

Very Short Answer Type Questions | Q 13 | Page 192

Name the central part of an atom where protons and neutrons are held together.

Very Short Answer Type Questions | Q 14 | Page 192

What are the various letters used by Bohr to represent electron shells in an atom?

Very Short Answer Type Questions | Q 15 | Page 192

Name the particles which actually determine the mass of an atom.

Very Short Answer Type Questions | Q 16 | Page 192

Name the positively charged particle present in the atoms of all the elements.

Very Short Answer Type Questions | Q 17 | Page 192

What is the Electronic Configuration of a Hydrogen Atom?

Very Short Answer Type Questions | Q 18 | Page 192

How many times is a proton heavier than an electron?

Very Short Answer Type Questions | Q 19 | Page 192

Name the gas which produces anode rays consisting of protons in the discharge tube experiment.

Very Short Answer Type Questions | Q 20 | Page 192

Which part of an atom was discovered by Rutherford's alpha particle scattering experiment?

Very Short Answer Type Questions | Q 21 | Page 192

What is the positive charge on the nucleus of an atom due to?

Very Short Answer Type Questions | Q 22 | Page 192

State the number of electrons present in the outermost shell of the atoms of the following elements :(i) Neon 
(ii) Chlorine

Very Short Answer Type Questions | Q 23 | Page 192

Which shell of an atom can accommodate a maximum of :
(a) 8 electrons ?
(b) 32 electrons ?

Very Short Answer Type Questions | Q 24 | Page 192

Name the shell of an atom which can accommodate a maximum of :
(a) 2 electrons ?
(b) 18 electrons ?

Very Short Answer Type Questions | Q 25.1 | Page 192

Which subatomic particle was discovered by : Chadwick ?

Very Short Answer Type Questions | Q 25.2 | Page 192

Which subatomic particle was discovered by : Thomson?

Very Short Answer Type Questions | Q 25.3 | Page 192

Which subatomic particle was discovered by : Goldstein ?

Very Short Answer Type Questions | Q 26.1 | Page 192

Name the subatomic particle whose relative charge is : +1

Very Short Answer Type Questions | Q 26.2 | Page 192

Name the subatomic particle whose relative charge is : –1

Very Short Answer Type Questions | Q 26.3 | Page 192

Name the subatomic particle whose relative charge is : 0

Very Short Answer Type Questions | Q 26.7 | Page 192

Fill in the blank of the following statement :

The anode rays obtained from hydrogen gas consist of particles called ________

Very Short Answer Type Questions | Q 27.1 | Page 192

Fill in the blanks- The number of protons in the nucleus of an atom is called its ....................

Very Short Answer Type Questions | Q 27.2 | Page 192

Fill in the blank of the following statement : 

The total number of protons and neutrons in the nucleus of an atom is called its _________.

Very Short Answer Type Questions | Q 27.3 | Page 192

Fill in the blanks of the following statements :

An atom has atomic mass number 23 and atomic number 11. The atom has_________ electrons.

Cathode rays are a beam of fast moving _________

The maximum number of electrons that can be accommodated in L shell are_________

The maximum number of electrons that can go into the M shell is _________

Very Short Answer Type Questions | Q 27.4 | Page 192

Fill in the blanks of the following statement :

An atom of an element has 11 protons, 11 electrons and 12 neutrons. The atomic mass of the atom is ___________.

Very Short Answer Type Questions | Q 27.5 | Page 192

Fill in the blank of the following statement :

 If the nucleus of an atom has atomic number 17, mass number 37 and there are 17 electrons outside the nucleus, the number of neutrons in it is __________.

Very Short Answer Type Questions | Q 27.6 | Page 192

Fill in the blank of the following statement :

All the mass of an atom is concentrated in a small region of space called the _____.

Very Short Answer Type Questions | Q 27.8 | Page 192

Fill in the blank of the following statement :

The subatomic particle not present in a hydrogen atom is ________

Very Short Answer Type Questions | Q 27.9 | Page 192

Fill in the blank of the following statement :

The electron has _________ charge, the proton has _________ charge, and the neutron has _________ charge.

Short Answer Type Questions | Q 28 | Page 192

What is an electron? State its relative mass and charge.

Short Answer Type Questions | Q 29 | Page 192

What is the absolute mass and charge of an electron?

Short Answer Type Questions | Q 30 | Page 192

Give the evidence for the existence of nucleus in an atom.

Short Answer Type Questions | Q 31 | Page 192

What important information is furnished about the nucleus of an atom by the alpha particle scattering experiment of Rutherford?

Short Answer Type Questions | Q 32 | Page 193

An element has an atomic number 12. How many electrons will be present in the K, L and M energy shells of its atom?

Short Answer Type Questions | Q 32 | Page 192

How was it shown that an atom has a lot of empty space within it?

Short Answer Type Questions | Q 33 | Page 192

Why is an atom neutral inspite of the presence of charged particles in it?

Short Answer Type Questions | Q 34 | Page 192

(a) Which of the nuclear particles is present in the same fixed number in the atoms of any particular element?

(b) What do we call this number which is characteristic of a particular element?

Short Answer Type Questions | Q 35 | Page 193

What is a proton? State its relative mass and charge.

Short Answer Type Questions | Q 36 | Page 193

What is the absolute mass and charge of a proton?

Short Answer Type Questions | Q 37 | Page 193

How does a proton differ from an electron?

Short Answer Type Questions | Q 38 | Page 193

State two observations which show that atom is not indivisible.

Short Answer Type Questions | Q 39.1 | Page 193

All the gases from cathode rays and anode rays when electricity is passed through them :What does the formation of cathode rays tell us about the atoms?

Short Answer Type Questions | Q 39.2 | Page 193

All the gases from cathode rays  anode rays when electricity is passed through them :

What does the formation of anode rays tell us about the atoms?

Short Answer Type Questions | Q 40 | Page 193

What do you understand by the term "electronic configuration" of an element? Write down the electronic configuration of oxygen (At. No. = 8).

Short Answer Type Questions | Q 41 | Page 193

An element has an atomic number 12. How many electrons will be present in the K, L and M energy shells of its atom?

Short Answer Type Questions | Q 42 | Page 193

(a) What is the nucleus of an atom and what is the nature of charge on it?

(b) Name the scientist who discovered the nucleus of atom.

Short Answer Type Questions | Q 43 | Page 193

Name the particles used by Rutherford in his experiment on the discovery of nucleus. Also state the charge on these particles.

Short Answer Type Questions | Q 44 | Page 193

An element has atomic number 13 and an atomic mass of 27.
(a) How many electrons are there in each atom of the element ?
(b) How are these electrons distributed in the various energy levels ?

Short Answer Type Questions | Q 45 | Page 193

Write the distribution of electrons in an atom of element whose atomic number is 18. What is special about the outermost electron shell (or valence shell) of the atom of this element?

Short Answer Type Questions | Q 46 | Page 193

What is a neutron? State its relative mass and charge.

Short Answer Type Questions | Q 47 | Page 193

Compare an electron, a proton and a neutron in respect of their relative masses and charges.

Short Answer Type Questions | Q 48 | Page 193

What is a proton? How does it differ from a neutron?

Short Answer Type Questions | Q 49 | Page 193

Compare an electron and a proton in respect of mass and charge.

Short Answer Type Questions | Q 50 | Page 193

Compare a proton and a neutron in respect of mass and charge.

Short Answer Type Questions | Q 51 | Page 193

How does an electron differ from a neutron?

Short Answer Type Questions | Q 52 | Page 193

State the location of electrons, protons and neutrons in an atom.

Short Answer Type Questions | Q 53 | Page 193

Fill in the following blanks :

Atomic Number Mass Number Protons Neutrons Electrons Symbol
10 22 _________ _________ _________ _________
Short Answer Type Questions | Q 54 | Page 193

Fill in the following blanks in respect of an atom of an element 

No. of protons No. of neutron Mass number Atomic number No. of electrons Symbol
11 12 ___________ ___________ ___________ ___________
Long Answer type Questions | Q 55 | Page 193

(a) What are cathode rays? What is the nature of charge on cathode rays?

(b) Explain how, cathode rays are formed from the gas taken in the discharge tube.

(c) What conclusion is obtained from the fact that all the gases from cathode rays?

Long Answer type Questions | Q 56.1 | Page 193

(a) Describe Thomson's model of the atom. Which subatomic particle was not present in Thomson's model of the atom?

Long Answer type Questions | Q 56.2 | Page 193

 The mass number of an element is 18. It contains 7 electrons. What is the number of protons and neutrons in it? What is the atomic number of the element?

Long Answer type Questions | Q 57.1 | Page 194

Describe the Rutherford's model of an atom. State one drawback of Rutherford's model of the atom.

Long Answer type Questions | Q 57.2 | Page 193

The mass number of an element is 23 and it contains 11 electrons. What is the number of protons and neutrons in it? What is the atomic number of the element?

Long Answer type Questions | Q 58.1 | Page 193

Describe Bohr's model of the atom. How did Neils Bohr explain the stability of atom?

Long Answer type Questions | Q 58.2 | Page 193

An element has an atomic number of 11 and its mass number is 23. What is the arrangement of electrons in the shells? State nuclear composition of an atom of the element.

Long Answer type Questions | Q 59 | Page 194

(a) What is meant by (i) atomic number, and (ii) mass number, of an element? Explain with the help of an example.

(b) What is the relation between the atomic number and mass number of an element?

(c) If an element M has mass number 24 and atomic number 12, how many neutrons does its atom contain?

Multiple Choice Questions | Q 60 | Page 194

Rutherford's alpha particle scattering experiment led to the discovery of :

  • Nucleus

  • Electrons

  • Protons

  • Neutrons

Multiple Choice Questions | Q 61 | Page 194

Which of the following is the correct electronic configuration of sodium?

  • 2, 8, 1

     

     

  • 8, 2, 1

  • 2, 1, 8

  • 2, 8, 2

Multiple Choice Questions | Q 62 | Page 194

The particle not present in an ordinary hydrogen atom is :

  • proton

  • neutron

  •  nucleus

  • electron

Multiple Choice Questions | Q 63 | Page 194

The subatomic particle called electron was discovered by :

  • J.J. Thomson

  • Neils Bohr

  • James Chadwick

  • E. Goldstein

Multiple Choice Questions | Q 64 | Page 194

Which of the following represents the correct electron distribution in magnesium ion?

  •  2, 8

  • 2, 8, 1

  •  2, 8, 2

  • 2, 8, 3

Multiple Choice Questions | Q 65 | Page 194

The correct electronic configuration of a chloride ion is :

  • 2, 8

  • 2, 8, 4

  • 2, 8, 8

  • 2, 8, 7

Multiple Choice Questions | Q 66 | Page 194

Goldstein's experiments which involved passing high voltage electricity through gases at very low pressure resulted in the discovery of :

  • electron

  • proton

  •  nucleus

  •  neutron

Multiple Choice Questions | Q 67 | Page 194

The number of electrons in the atom of an element X is 15 and the number of neutrons is 16. Which of the following is the correct representation of an atom of this element ?

  • `""_15^31"X"`

  • `""_16^31"X"`

  • `""_15^16"X"`

  • `""_16^15"X"`

Multiple Choice Questions | Q 68 | Page 194

The ion of an element has 3 positive charges. The mass number of atom of this element is 27 and the number of neutrons is 14. What is the number of electrons in the ion?

  • 13

  • 10

  • 14

  • 16

Multiple Choice Questions | Q 69 | Page 194

The first model of an atom was given by :

  • Neils Bohr

  • Ernest Rutherford

  • J.J. Thomson

  • Eugen Goldstein

Multiple Choice Questions | Q 70 | Page 194

Which of the following statement is always correct?

  • an atom has equal number of electrons and protons

  • an atom has equal number of electrons and neutrons

  • an atom has equal number of protons and neutrons

  • an atom has equal number of electrons, protons and neutrons

Question Based on High order Thinking skills ( Hot Questions) | Q 71 | Page 194

From the symbol `""_15^31"P"`, state :
(i) mass number of phosphorus,
(ii) atomic number of phosphorus, and
(iii) electron configuration of phosphorus.

Question Based on High order Thinking skills ( Hot Questions) | Q 72 | Page 194

The atom of an element X has 7 electrons in its M shell.
(a) Write the electronic configuration of element X.
(b) What is the atomic number of element X?
(c) Is it a metal or a non-metal?
(d) What type of ion will be formed by an atom of element X? Write the symbol of the ion formed.
(e) What could element X be?

Question Based on High order Thinking skills ( Hot Questions) | Q 73 | Page 194

An atom of element E contains 3 protons, 3 electrons and 4 neutrons :
(a) What is its atomic number?
(b) What is its mass number?
(c) Write the electronic configuration of the element E.
(d) State whether element E is a metal or non-metal. Why?
(e) What type of ion, cation or anion, will be formed by an atom of element E? Why
(f) Write the symbol of the ion formed by an atom of element E.
(g) What could element X be?

Question Based on High order Thinking skills ( Hot Questions) | Q 74 | Page 195

An atom of an element X may be written as `""_9^4"X"`
(a) What does the figure 9 indicate?
(b) What does the figure 4 indicate?
(c) What is the number of protons in atom X?
(d) What is the number of neutrons in atom X?
(e) What is the number of electrons in atom X?
(f) How many electrons are there in the outermost shell of an atom of element X?
(g) Write the symbol of ion formed by an atom of element X.

Question Based on High order Thinking skills ( Hot Questions) | Q 75 | Page 195

The electronic configuration of an element Z is 2, 8, 8.
(a) What is the atomic number of the element?
(b) State whether element Z is a metal or a non-metal.
(c) What type of ion (if any) will be formed by an atom of element Z? Why?
(d) What is special about the outermost electron shell of the atom of this element?
(e) Give the name and symbol of element Z.
(f) Name the group of elements to which Z belongs.

Chapter 4: Structure of the Atom Exercise Very Short Answer Type Questions, Short Answer Type Questions, Long Answer Type Questions, Multiple Choice Questions( MCQs), Questions Based On High Order Thinking Skills (HOTS) solutions [Pages 210 - 213]

Very Short Answer Type Questions | Q 1 | Page 210

The total number of electrons in a nitrogen atom is 7. Find the number of valence electrons in it.

Very Short Answer Type Questions | Q 2 | Page 210

What is the general name of the elements having 8 electrons in the valence shell of their atoms?

Very Short Answer Type Questions | Q 3 | Page 210

Which noble gas has less than 8 electrons in the valence shell of its atom? What is this number?

Very Short Answer Type Questions | Q 4 | Page 210

State one use of radioactive isotopes in medicine.

Very Short Answer Type Questions | Q 5 | Page 210

Give one example of a radioactive isotope which is used as a fuel in the reactors of nuclear power plants.

Very Short Answer Type Questions | Q 6 | Page 210

Name the Radioactive Isotope Which is Used in the Treatment of Cancer.

Very Short Answer Type Questions | Q 7 | Page 210

Which radioactive isotope is used to determine the activity of thyroid gland?

Very Short Answer Type Questions | Q 8 | Page 210

State one use of radioactive isotopes in industry.

Very Short Answer Type Questions | Q 9 | Page 210

State whether the following statement is true or false :
Radioactive isotope of iodine is used for making the medicine called tincture iodine.

Very Short Answer Type Questions | Q 10 | Page 210

What name is given to those atoms which contain the same number of protons and electrons but different number of neutrons?

Very Short Answer Type Questions | Q 11 | Page 210

What is the relationship between an atom containing 11 protons, 11 electrons and 11 neutrons, and another atom containing 11 protons, 11 electrons and 12 neutrons?

Very Short Answer Type Questions | Q 12 | Page 210

What name is given to the pair of atoms such as `""_7^14"N"` and `""_7^15"N"` ?

Very Short Answer Type Questions | Q 13 | Page 210

What name is given to those isotopes which have unstable nuclei and emit various types of radiations ?

Very Short Answer Type Questions | Q 14 | Page 210

Fill in the following blanks in respect of an atom of an element :

Number of protons Number of neutrons Mass number Atomic number Number of electron Valency
11 12 _________ _________ _________ _________
Very Short Answer Type Questions | Q 15.1 | Page 210

Complete the Following Statements :
Magnesium has 2 valence electrons in the ............. shell.

The valency of nitrogen in N2 molecule is .............

Very Short Answer Type Questions | Q 15.2 | Page 210

Complete the following statements :
Isotopes have different mass numbers because their nuclei contain different number of ............

Some boron atoms have mass number 10 and some have mass number 11. These boron atoms with different mass numbers are called .............

Short Answer Type Questions | Q 16 | Page 210

The nucleus of an atom has 5 protons and 6 neutrons. What would be the (a) atomic number, (b) mass number, (c) the number of electrons, and (d) the number of valence electrons, per atom of this element?

Short Answer Type Questions | Q 17 | Page 210

Write the electronic configuration of the element with atomic number 17. Indicate the valency of the element.

Short Answer Type Questions | Q 18 | Page 210

The atomic number of an element X is 16.
(a) Write down the electronic configuration of X.
(b) What will be the valency of X ?

Short Answer Type Questions | Q 19 | Page 211

What valencies will be shown by the elements A, B, C, D and E having atomic number 2, 4, 8, 10 and 13 respectively.

Short Answer Type Questions | Q 20 | Page 211

Give one use each of the following radioactive isotopes :
(a) Uranium-235
(b) Cobalt-60

Short Answer Type Questions | Q 21 | Page 211

Explain why `""_1^3"H"` and `""_2^3"H"` are not considered isotopes.

Short Answer Type Questions | Q 22 | Page 211

What is the reason for the different atomic masses of the isotopes of an element ?

Short Answer Type Questions | Q 23 | Page 211

What is the reason for the identical chemical properties of all the isotopes of an element ? Explain with the help of an example.

Short Answer Type Questions | Q 24 | Page 211

What is the reason for the slightly different physical properties of all the isotopes of an element ?

Short Answer Type Questions | Q 25 | Page 211

Explain why, the atomic masses of many elements are in fractions and not whole numbers.

Short Answer Type Questions | Q 26 | Page 211

Which of the following are isotopes and which are isobars ?
Argon, Deuterium, Calcium, Tritium, Protium

Short Answer Type Questions | Q 27 | Page 211

Hydrogen has three isotopes written as : 
`""_1^1"H"`  `""_1^2"H"` `""_1^3"H"`

Explain why :
(i) these isotopes have almost identical chemical properties.
(ii) they are electrically neutral.

Short Answer Type Questions | Q 28 | Page 211

Given that the percentage abundance of the isotope `""_10^20"Ne"` is 90% and that of the isotope `""_10^22"Ne"` is 10%, calculate the average atomic mass of neon.

Short Answer Type Questions | Q 29 | Page 211

What are isobars ? Explain with an example.

Short Answer Type Questions | Q 30 | Page 211

For the symbols H, D and T, write the subatomic particles (protons, neutrons and electrons) found in each one of them.

Short Answer Type Questions | Q 31 | Page 211

An element has Z = 7. What is the valency of the element ? Also name the element.

Long Answer Type Questions | Q 32 | Page 211

(a) What are valence electrons? Where are valence electrons situated in an atom ?
(b) What is the number of valence electrons in the atoms of an element having atomic number 13 ? Name the valence shell of this atom.

Long Answer Type Questions | Q 33 | Page 211

(a) What are isotopes ? Explain by giving an example.

(b) Give one similarity and one difference between a pair of isotopes.

(c) Give the number of protons, neutrons and electrons per atom in the two isotopes of chlorine `""_17^35"Cl"` and `""_17^35"Cl"`.

Long Answer Type Questions | Q 34 | Page 211

(a) What are radioactive isotopes ? Give two examples of radioactive isotopes.

(b) Give any two uses of radioactive isotopes.

(c) An element Z contains two naturally occurring isotopes `""_17^35"Z"` and `""_17^37"Z"`. If the average atomic mass of this element be 35.5 u, calculate the percentage of two isotopes.

Long Answer Type Questions | Q 35 | Page 211

(a) Define valency of an element. What valency will be shown by an element having atomic number 14 ?
(b) What is the relation between the valency of an element and the number of valence electrons in its atoms ? Explain with examples.

Multiple Choice Questions( MCQs) | Q 36 | Page 211

The mass number of two atoms X and Y is the same (40 each) but their atomic number are different (being 20 and 18 respectively). X and Y are examples of :

  • chemically similar atoms

  • isotopes

  •  solid and liquid metals

  • isobars

Multiple Choice Questions( MCQs) | Q 37 | Page 211

Which of the following statement is correct about the atom of an element ?

  • an atom can have only protons and neutrons but no electrons.

  • an atom can have only electrons and neutrons but no protons

  • an atom can have only electron and proton but no neutron

  • an atom must always have a proton, neutron and electron

Multiple Choice Questions( MCQs) | Q 38 | Page 212

There are two species represented as 35Cl and 37Cl. Which of the following statement is correct regarding these species ?

  • hey have different chemical properties

  •  their physical properties are the same

  • they have the same number of protons

  • they are isobars of the same element

Multiple Choice Questions( MCQs) | Q 39 | Page 212

The radioactive isotope used in the treatment of cancer is :

  • plutonium-239

  • arsenic-74

  •  cobalt-60

  • iodine-131

Multiple Choice Questions( MCQs) | Q 40 | Page 212

Elements having valency 'one' are :

  • always metals

  • always non-metals

  • always metalloids

  • either metals or non-metals

Multiple Choice Questions( MCQs) | Q 41 | Page 212

In a sample of ethyl ethanoate (CH3COOC2H5), the two oxygen atoms have the same number of electrons but different number of neutrons. Which of the following is the correct reason for it ?

  • one of the oxygen atoms has gained electrons

  • one of the oxygen atoms has gained protons

  • the two oxygen atoms are isotopes

  • the two oxygen atoms are isobars

Multiple Choice Questions( MCQs) | Q 42 | Page 212

Which of the following elements does not exhibit electrovalency ?

  • calcium

  • chromium

  •  carbon

  • cadmium

Multiple Choice Questions( MCQs) | Q 43 | Page 212

The number of valence electrons in a graphite atom is :

  • 2

  • 4

  • 3

  •  5

Multiple Choice Questions( MCQs) | Q 44 | Page 212

The atomic number of four elements A, B, C and D are 12, 13, 15 and 3 respectively. The element which cannot form a cation is :

  • A

  • B

  • C

  • D

Multiple Choice Questions( MCQs) | Q 45 | Page 212

The number of valence electrons in a sulphide ion, S2–, is :

  • 16

  • 10

  • 9

  • 8

Multiple Choice Questions( MCQs) | Q 46 | Page 212

For an element, Z = 9. The valency of this element will be :

  • 4

  • 2

  • 1

  • 3

Multiple Choice Questions( MCQs) | Q 47 | Page 212

Four elements W, X, Y and Z contain 8, 11, 9 and 17 protons per atom respectively. The element which cannot form an anion is most likely to be :

  • W

  • X

  • Y

  • Z

Multiple Choice Questions( MCQs) | Q 48 | Page 212

The four atomic species can be represented as follows. Out of these, the two species which can be termed isobars are :

(i)`""_60^201"X"`

(ii)`""_61^200"X"`

(iii)`""_58^200"X"`

(iv)`""_60^203"X"`

  • (i) and (ii)

  • (ii) and (iii)

  • (i) and (iii)

  • (i) and (iv)

Multiple Choice Questions( MCQs) | Q 49 | Page 212

There are four elements P, Q, R and S having atomic numbers of 4, 18, 10 and 16 respectively. The element which can exhibit covalency as well as electrovalency will be :

  • P

  • Q

  • R

  • S

Multiple Choice Questions( MCQs) | Q 50 | Page 212

The atomic number of an element X is 8 and that of element Y is 4. Both these elements can exhibit a valency of :

  • 1

  • 2

  • 3

  • 4

Multiple Choice Questions( MCQs) | Q 51 | Page 212

The isotopes of an element contain :

  • same number of neutrons but different number of protons

  • same number of neutrons but different number of electrons

  • different number of protons as well as different number of neutrons

  •  different number of neutrons but same number of protons

Questions Based On High Order Thinking Skills (HOTS) | Q 52 | Page 212

What is the number of valence electrons in :
(a) sodium ion, Na+
(b) oxide ion, O2–

Questions Based On High Order Thinking Skills (HOTS) | Q 53 | Page 212

Atom A has a mass number 209 and atomic number 82.
Atom B has a mass number 209 and atomic number 83.
(i) How many protons atom A has ?
(ii) How many protons atom B has ?
(iii) Are atoms A and B isotopes of the same element ?

Questions Based On High Order Thinking Skills (HOTS) | Q 54 | Page 213

Which of the following pairs are isotopes ? Give reasons for your choice :

(i) `""_26^58"A"`,  `""_28^58"B"` or (ii) `""_35^79"X"`,  `""_35^80"Y"` 

Questions Based On High Order Thinking Skills (HOTS) | Q 55 | Page 213

Three different atoms of oxygen are represented as : 
`""_8^16"O"`, `""_8^17"O"`, `""_8^16"O"`
(i) What do the subscripts (lower figures) and superscripts (upper figures) represent ?
(ii) What factor is responsible for the change in the superscripts 16, 17 and 18, though the element is the same ?
(iii) What is the usual name for such atoms of an element ?
(iv) Give the nuclear composition of  `""_8^16"O"`.

Questions Based On High Order Thinking Skills (HOTS) | Q 56 | Page 213

The atomic species A and B have different number of protons but the same number of nucleons. On the other hand, the atomic species X and Y have the same number of protons but different number of nucleons. Which pair is an example of isobars ? Why ?

Questions Based On High Order Thinking Skills (HOTS) | Q 57 | Page 213

Composition of the nuclei of two atomic species A and B is given as under  :

  A B
Protons : 18 20
Neutrons : 22 20

Give the mass numbers of A and B. What is the relation between the two species and which element or elements they represent ?

Questions Based On High Order Thinking Skills (HOTS) | Q 58 | Page 213

Which of the following pairs are isobars ?
(i) `""_26^58"A"`, `""_28^58"B"`

(ii) `""_35^79"X"`, `""_35^80"Y"`
Give reasons for your choice.

Questions Based On High Order Thinking Skills (HOTS) | Q 59 | Page 213

The number of protons, neutrons and electrons in particles A to E are given below :

Particle Protons Neutrons Electrons
A 17 18 17
B 3 4 2
C 18 22 18
D 17 20 17
E 9 10 10

Giving reasons, find a pair of isotopes from the above particles.

Questions Based On High Order Thinking Skills (HOTS) | Q 60 | Page 213

The composition of two atomic particles is given below :

  X Y
Protons : 8 8
Neutrons : 8 9
Electrons : 8 8

(i) What is the mass number of X ?

(ii) What is the mass number of Y ?

(iii) What is the relation between X and Y ?

(iv) Which element/elements do they represent ?

Chapter 4: Structure of the Atom

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Lakhmir Singh Class 9 Chemistry - Science Part 2

Class 9 Chemistry - Science Part 2 - Shaalaa.com

Lakhmir Singh solutions for Class 9 Science chapter 4 - Structure of the Atom

Lakhmir Singh solutions for Class 9 Science chapter 4 (Structure of the Atom) include all questions with solution and detail explanation. This will clear students doubts about any question and improve application skills while preparing for board exams. The detailed, step-by-step solutions will help you understand the concepts better and clear your confusions, if any. Shaalaa.com has the CBSE Class 9 Chemistry - Science Part 2 solutions in a manner that help students grasp basic concepts better and faster.

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Concepts covered in Class 9 Science chapter 4 Structure of the Atom are Eugen Goldstein, Concept of Electron, Concept of Proton, Structure of Atom Numericals, Concept of Isobars, Concept of Isotopes, Mass Number, Atomic Number, Valency, Concept of Electrons Distributed in Different Orbits (Shells), Structure of an Atom - Neutrons, Structure of an Atom - Bohr’S Model of Atom, Structure of an Atom - Rutherford’S Model of an Atom, Structure of an Atom - Thomson’S Model of an Atom, Charged Particles in Matter, Structure of Atom Introduction.

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