9th Std Science Solution in English | Lesson.13 Chemical bonding

Lesson 13 Chemical Bonding

9th Science Guide Chemical Bonding: In this post, we will provide you with a comprehensive understanding of chemical bonding. We will cover various aspects related to bonding between atoms and molecules, accompanied by clear and concise explanations. Whether you are preparing for an exam or seeking a better grasp of this topic, this guide is designed to assist you in your studies.

Chemical Bonding Book Back Answer

Below, you can find the answers for the Lesson Chemical Bonding following sections: “Choose the Correct Answer,” “Fill in the Blanks,” “State Whether True or False,” and so on.

I. Choose the Correct Answer:

1. Number of valence electrons in carbon is

1. 2
2. 4
3. 3
4. 5

Ans: 4

2. Sodium having atomic number 11, ready to __________ electron/electrons to attain the nearest Noble gas electronic configuration.

1. gain one
2. gain two
3. lose one
4. lose two

Ans: lose one

3. The element that would form anion by gaining electrons in a chemical reaction is __________

1. Potassium
2. Calcium
3. Fluorine
4. Iron

Ans: Fluorine

4. Bond formed between a metal and non metal atom is usually __________

1. ionic bond
2. covalent bond
3. coordinate bond

Ans: ionic bond

5. __________ compounds have high melting and boiling points.

1. Covalent
2. Coordinate
3. Ionic

Ans: Ionic

6. Covalent bond is formed by __________

1. transfer of electrons
2. sharing of electrons
3. sharing a pair of electrons

Ans: sharing of electrons

7. Oxidising agents are also called as ___________ because they remove electrons form other substances.

1. electron donors
2. electron acceptors

Ans: electron acceptors

8. Elements with stable electronic configurations have eight electrons in their valence shell. They are _______

1. Halogens
2. Metals
3. Noble gases
4. non metals

Ans: Noble gases

9. Atoms having 1,2 or 3 electrons in its valence shell will readily form ________

1. cation
2. anion

Ans: cation

II. Answer in Brief

1. How do atoms attain Noble gas electronic configuration?

Atoms can combine either by transfer of valence electrons from one atom to another or by sharing of valence electrons in order to achieve the stable outer shell of eight electrons

2. CCl₄ is insoluble in water but NaCl is soluble in water. Give reason.

• CCl₄ is a Covalent compound but NaCl is an Ionic Compound.
• Water is a polar solvent so NaCl is soluble in water.
• CCl₄ is soluble in nonpolar solvent.

3. Explain Octet rule with an example.

The octet rule is a chemical rule of thumb that reflects observation that atom of maingroup elements tend to combine in such a way that each atom has eight electrons in its valance shell, giving it the same electron configuration as a noble gas.

4. Write a note on different types on bonds?

• Ionic bonds
• Covalent bonds
• Co-Ordinate Covalent bond.

5. Correct the wrong statements.

a. Ionic compounds dissolve in non polar solvents

Ionic compounds dissolve in polar solvents

b. Covalent compounds conduct electricity in molten or solution state.

Covalent compounds do not conduct electricity in molten or solution state.

6. Complete the table given below.

Element	Atomic number	Electron distribution	Valence electrons	Lewis dot structure
Lithium	3	2,1	1
Boron	5	2,3	3
Oxygen	8	2,6	6

7. Draw the electron distribution diagram for the formation of Carbon dioxide (CO₂) molecule.

8. Fill in the following table according to the type of bonds formed in the given molecule.

CaCl₂, H₂O, CaO, CO, KBr, HCl, CCl₄, HF, CO₂, Al₂Cl₆

9. Choose the correct answer form the choices given below.

The property which is characteristics of an Ionic compound is that

1. it ofen exists as gas at room temperature
2. it is hard and brittle
3. it undergoes molecular reactions
4. it has low melting point

Ans: it is hard and brittle

10. Identify the following reactions as oxidation or reduction

a. Na → Na⁺ + e^–

Oxidation reactions

b. Fe³+ + 2e^– → Fe⁺

Reduction reactions

11. Identify the compounds as Ionic/Covalent/Coordinate based on the given characteristics.

a. Soluble in non polar solvents –

Covalent bond

b. undergoes faster/instantaneous reactions –

Ionic bond

c. Non-conductors of electricity

Covalent bond

d. Solids at room temperature –

Co-ordinate Covalent bond

12. An atom X with atomic number 20 combines with atom Y with atomic number 8. Draw the dot structure for the formation of the molecule XY.

CaO

13. Considering MgCl₂ as an ionic compound and CH₄ as a covalent compound give any two differences between these two compounds.

14. Why are Noble gases inert in nature?

All noble gases have incomplete valance shell, and tends to stable electronic configuration. so Noble gas inert in nature.

15. Find the odd one out.

a. H₂,  Cl₂,  NaCl,  O₂,  N₂

NaCl

b. H₂O₂,  MnO₄^–,  LiAlH₄, Cr₂O₂^2–

LiAlH₄

III. Answer in detail

1. List the differences between Ionic and Covalent compounds.

2. Give an example for each of the following statements.

a. a compound in which two Covalent bonds are formed

O₂ O = O

b. a compound in which one ionic bond is formed

HCl

c. a compound in which two Covalent and one Coordinate bonds are formed

CO

d. a compound in which three covalent bonds are formed

N = N

e. a compound in which Coordinate bond is formed

NH₄+

3. Identify the incorrect statement and correct them.

a. Like covalent compounds, Coordinate compounds also contain charged particles (ions), so they are good conductors of electricity.

Like covalent compounds, Coordinate compounds also contain charged particles (ions), so they are bad conductors of electricity.

b. Ionic bond is a weak bond when compared to Hydrogen bond

Ionic bond is a strong bond when compared to Hydrogen bond.

c. Ionic or electrovalent bonds are formed by mutual sharing of electrons between atoms.

Ionic or electrovalent bonds are formed by the mutual transfer of electrons between atoms.

d. Loss of electrons is called Oxidation and the Gain of electrons is called Reduction.

d. Loss of electrons is called Oxidation and Gain of electrons is called Reduction. (statement Correct)

e. The electrons which are not involved in bonding are called valence electrons.

The electrons which are not involved in bonding are called lone pair electrons.

4. Discuss in brief the properties of Coordinate covalent compounds.

Characteristics of coordinate covalent compounds

The compounds containing coordinate covalent bonds are called coordinate compounds.

a. Physical state

These compounds exist as gases, liquids, or solids.

b. Electrical conductivity

Like covalent compounds, coordinate compounds also do not contain charged particles (ions), so they are bad conductors of electricity.

c. Melting point

These compounds have melting and boiling points higher than those of purely covalent compounds but lower than those of purely Ionic compounds.

d. Solubility

Insoluble in polar solvents like water but are soluble in non-polar solvents like benzene, CCl₄, and toluene.

e. Reactions

Coordinate covalent compounds undergo molecular reactions which are slow.

5. Find the oxidation number of the elements in the following compounds.

a. C in CO₂

b. Mn in MnSO₄

c. N in HNO₃

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Last Updated: 2nd July 2023