Category: Class 11 Chemistry Objective Questions

Chemistry Assessment Questions and Answers on “Law of Chemical Equilibrium and Equilibrium Constant”.

1. A reaction is given by aA + bB → cC + dD. How do you represent an equilibrium constant?
a) [A]^a[B]^b/[C]^c[D]^d
b) [C]^c[D]^d/[A]^a[B]^b
c) [A][B]/[C][D]
d) [C][D]/[A][B]
Answer: b
Clarification: An equilibrium constant in a chemical reaction As given by the ratio of Forward reaction rate by backward reaction rate its units are (mol/L)^Δn_g, where Δn_g is moles of products – moles of reactants which are in the gaseous state only.

2. The value of equilibrium constant for different chemical reactions at a particular temperature is ____________
a) constant
b) unique
c) the same
d) cannot say
Answer: b
Clarification: The value of the equilibrium constant changes with temperature i.e. it’s different for different temperatures and is unique for every reaction at a constant temperature or given temperature.

3. What does it indicate having a higher equilibrium constant?
a) reaction occurs faster
b) rate of backward reaction is faster
c) both the backward and forward reactions are equal
d) reaction may be slower than usual
Answer: a
Clarification: As we know that the equilibrium constant is the ratio of the forward reaction rate to the backward reaction rate. Having higher equilibrium constant depicts that the reaction that is forward occurring faster then the backward one and the extension of completion of the reaction is more.

4. The equilibrium constant of a reaction is 20 units and the equilibrium constant of other reaction is 30 units when both the reactions are added up together then the equilibrium constant of the resultant reaction is given by _____________
a) 20 units
b) 600 units
c) 50 units
d) 10 units
Answer: b
Clarification: When the reaction can be expressed as the sum of two other reactions, the equilibrium constant of the overall reaction is equal to the product of equilibrium constants of individual reactions, so 20 units x 30 units = 600 units.

5. If the initial concentrations of reactants in a reaction increase then the equilibrium constant ____________
a) also increases
b) decreases
c) remains constant
d) may increase or decrease
Answer: c
Clarification: The equilibrium constant of a chemical reaction is independent of the initial concentrations of the reactants. So when the initial concentrations of the reactants increase in a reaction the equilibrium constant remains the same.

6. If we use activities in place of molar concentration in an equilibrium constant expression then what is the dimension of k?
a) it becomes dimensionless
b) the same units of molar concentration
c) units are related to the activity
d) cannot predict it
Answer: a
Clarification: In equilibrium constant expression of a chemical reaction, (equilibrium constant is represented by the letter K) if the activities are used in place of the molar concentration K becomes dimensionless, that means it has no dimensions.

7. What is the equilibrium constant of the following reaction: 4NH₃ + 5O₂ → 4NO + 6H₂O?
a) [NO][H₂O]/[NH₃][O₂]
b) [C]^c[D]^d/[A]^a[B]^b
c) [NO₄[H₂]⁶/NH₃]⁴[O₂]⁵
d) [NO]⁴[H₂O]⁶/[NH₃]⁴[O₂]⁵
Answer: d
Clarification: the above given chemical reaction 4NH₃ + 5O₂ → 4NO + 6H₂O is in the form of aA + bB → cC + dD. We know that the equilibrium constant of this reaction is [C]^c[D]^d/[A]^a[B]^b, show the required answer is [NO]⁴[H₂O]⁶/[NH₃]⁴[O₂]⁵.

8. for the reaction H_2(g) + Br_2(g) ↔ 2HBr_(g) the equilibrium constant is given as 0.04 then what is the equilibrium constant for the reaction 2HBr_(g) ↔ H_2(g) + Br_2(g)?
a) 0.04
b) 4
c) 25
d) 100
Answer: c
Clarification: In a chemical reaction if the equilibrium constant for a backward reaction is given by k then the equilibrium constant for the forward reaction is given by 1/k, so your the resultant answer becomes 1/0.04 = 25.

9. Given that at 800k the concentrations are as follows: N₂=3.0 × 10^–3M, O₂ = 4.2 × 10^–3M and NO = 2.8 × 10^–3M, what is the equilibrium constant for the reaction N_2(g) + O_2(g) (rightleftharpoons ) 2NO_(g)?
a) 0.622
b) 0.6
c) 0.63
d) 0.94
Answer: a
Clarification: For the reaction, N_2(g) + O_2(g) (rightleftharpoons ) 2NO_(g), the equilibrium constant is given by [NO]²/[N₂][O₂]. So the equilibrium constant K is given by (2.8 × 10^–3 M)(2.8 × 10^–3 M)/(3.0 × 10^–3 M)(4.2 × 10^–3 M) = 0.622, there are no units as Δn_g = 0.

10. If the chemical reaction is: aA + bB → cC + dD and K is the equilibrium constant. Then what is the equilibrium constant of the reaction naA + nbB → ncC + ndD?
a) K
b) nK
c) Kⁿ
d) K/n
Answer: c
Clarification: If a chemical reaction is multiplied by a constant then the equilibrium constant of the particular chemical reaction is raised to the power of the constant by which the chemical reaction is multiplied, so here and is a constant and equilibrium constant of the reaction is kⁿ.

Chemistry Assessment Questions,

Chemistry Exam Questions and Answers for Class 11 on “Hydrogen – Hydrides”.

1. Which of the following acts as a ligand in complex Hydrides?
a) H₂
b) H^–
c) H⁺
d) H
Answer: b
Clarification: In complex hydrides like Lithium aluminium hydride or lithium sodium hydride, the hydrogen acts as a ligand and it is attached to the central atom in complex hydrides, which are salt-like substances.

2. (BeH₂)_n is a ______________
a) covalent hydride
b) polymeric hydride
c) ionic hydride
d) metallic hydride
Answer: b
Clarification: Polymeric hydrides are formed by elements having electronegativity in the range of 1.4 to 2.0. Examples of polymeric hydrides are (BeH₂)_n, (AlH₃)_n etc. They are joined to each other through hydrogen bonding in order to form a larger unit.

3. The oxidation state of hydrogen in hydrides is -1.
a) true
b) false
Answer: a
Clarification: The compounds of hydrogen with metals and nonmetals are called hydrides and their Oxidation state is -1. The examples are sodium hydride, calcium hydride, magnesium hydride etc. There are many types of hydrides like ionic hydrides, molecular hydrides covalent hydrides etc.

4. Hydrides made from group 1 and 2 are known as ___________
a) complex hydrides
b) ionic hydrides
c) metallic hydrides
d) covalent hydrides
Answer: b
Clarification: Ionic hydrides are formed by elements of group 1 and 2 except beryllium and magnesium, by heating them in hydrogen. They are white colourless crystalline solid having a high melting point and boiling point and they are easily decomposed by water, carbon dioxide or Sulphur dioxide.

5. What is used for removing the last traces of water from organic compounds?
a) Hydrogen
b) Lithium aluminium hydride
c) Ionic hydrides
d) Molecular hydrides
Answer: c
Clarification: Ionic hydrides are very strong reducing agents. Alkali metal hydrides are used for making Lithium aluminium hydride, sodium Boron hydride etc and they are also used for removing last traces of water from organic compounds.

6. Molecular hydrides of formed from ______________
a) f-block elements
b) p- block elements
c) d-block elements
d) s- block elements
Answer: b
Clarification: Molecular hydrides are also called as covalent hydrides and they are formed by elements of p-block those having higher electronegativity than hydrogen. They are again divided into electron deficient hydrides, electron precise hydrides and electron rich hydrides.

7. Which of the following is an example Of electron rich hydride?
a) methanol
b) methane
c) aluminium hydride
d) ammonia
Answer: d
Clarification: Electron rich hydrides are the hydrides which have a greater number of electrons than required to form normal covalent bonds. Examples are the hydrides of group 15, 16 and 17, the excess electrons in these hydrides, are present as lone pairs of electrons.

8. Methane is a electron _________ hydride.
a) poor
b) deficient
c) rich
d) precise
Answer: d
Clarification: Electron precise hydrides are the hydrides which have an exact number of electrons, that are needed to form normal covalent bonds. Few examples are the hydrides of group 14 like methane, Silicon hydride etc.

9. Aluminium hydride is an electron deficient hydride.
a) true
b) false
Answer: a
Clarification: Aluminium hydride is a molecular hydride, because it does not have a required number of electrons to form the normal covalent bonds. So, aluminium hydride is also called as an electron-deficient hydride, therefore the above statement is true.

10. Interstitial hydrides are also called as ____________
a) complex hydrides
b) molecular hydrides
c) ionic hydrides
d) metallic hydrides
Answer: d
Clarification: Metallic hydrides are also known as interstitial hydrides, these are formed when the transition metals and the rare Earth metals combine with hydrogen. Molecular hydrides are nothing but covalent hydrides, where are ionic hydrides are formed from S block elements.

11. Metallic hydrides are powerful _____________ agents.
a) oxidizing
b) reducing
c) combining
d) separating
Answer: a
Clarification: The metallic hydrides are powerful reducing agents. They are formed from the combination of transition metals and rare Earth metals with hydrogen and they also exhibit metallic properties. They are non-stoichiometric hydrides.

12. LaH_2.76 is an example of _______
a) molecular hydrides
b) metallic hydrides
c) covalent hydrides
d) ionic hydrides
Answer: b
Clarification: The metallic interstitial hydrides’ composition varies with temperature and pressure, they are non-stoichiometric in nature and example for this is LaH_2.76. These hydrides are formed when transition metals and rare Earth metals combine with hydrogen.

13. The hydride gap is related to group ________
a) 7, 8
b) 7, 9
c) 7, 8, 9
d) 8, 9
Answer: c
Clarification: Metals of the group 7, 8 and 9 do not form hydrides under standard temperature and pressure and this region of the periodic table is called hydride gap. So the hydride gap is related to group 7, 8 and 9.

To practice Chemistry Exam Questions and Answers for Class 11,

Chemistry Multiple Choice Questions on “p-Block Elements – Allotropes of Carbon”.

1. Which of the following is the chemical formula of fullerenes?
a) C₀
b) C₆
c) C
d) C₆₀
Answer: d
Clarification: A Fullerene is a crystalline form of allotropic carbon, which is the only pure form of carbon. It is a C₆₀ molecule which is used in microscopic ball bearings, lightweight batteries, in the synthesis of new plastics and new drugs.

2. Half many five-membered rings are there in fullerenes?
a) 34
b) 15
c) 12
d) 10
Answer: c
Clarification: The Fullerenes are C₆₀ molecules which contain 12 five-membered rings and 20 six remembered rings, the five-membered rings are connected to six-membered rings while six-membered rings are connected to both five and six-membered rings.

3. What is the suspension of graphite in water known as?
a) Gaseous bag
b) Aqua Dag
c) Oil Dag
d) Liquid Dag
Answer: b
Clarification: Graphite is a form of crystalline allotropes of carbon the suspension of graphite in water is known as aqua dag and the suspension of graphite in oil lubricants is known as oil Dag. Aqua dag is commonly used in cathode ray tubes.

4. Bituminous is a common type of _____________
a) calcium
b) borax
c) coal
d) coke
Answer: c
Clarification: The different types of coal are Peat 60% of carbon, lignite 70% of carbon, bituminous 78% of carbon, semi-bituminous 83% of carbon and anthracite 90% of carbon. Among them, bituminous is the most common variety of coal.

5. Wood Charcoal is an allotrope of _____________
a) carbon
b) silicon
c) nitrogen
d) germanium
Answer: a
Clarification: Wood Charcoal is obtained by heating wood strongly in the absence of air. When heated with steam, it becomes more activated and it is used to remove coloring matters and audio odouiferous gases. It is an allotrope of carbon which is in amorphous form.

6. Bone black is used in the manufacture of pyridine.
a) True
b) False
Answer: a
Clarification: Bone black or animal Charcoal is obtained by destructive distillation of bones in iron retort by-products are bone oil and pyridine. It is used as adsorbent on burning, it gives Bone ash which is calcium phosphate and used in the manufacture of phosphorus and phosphoric acid.

7. Which of the following is an amorphous allotrope of carbon?
a) Diamond
b) Fullerenes
c) Graphite
d) Lampblack
Answer: d
Clarification: Diamond, fullerenes come and graphite are crystalline allotropes of carbon whereas lampblack is an amorphous form of carbon, which is obtained by burning vegetable oils in a limited supply of air and it is also used in the manufacture of printing ink, black paint, varnish, and carbon paper.

8. Carbon black is the same as coke.
a) False
b) True
Answer: a
Clarification: Coke is obtained by destructive distillation of coal whereas carbon black is obtained by burning natural gas in a limited supply of air and then it is added to rubber mixture for making automobile tires. Both are amorphous forms of allotropic carbon but they are not the same.

9. Which of the following allotropes of carbon are hard in nature?
a) Charcoal
b) Diamond
c) Graphite
d) Fullerenes
Answer: b
Clarification: The crystalline form of allotropic carbon is diamond, it is the hardest and has a three-dimensional polymeric structure in which hybridization of carbon is sp³. It is covalent solid, melting point is 3650-degree centigrade and it is also a bad conductor of heat and electricity.

10. Which of the following is known as the Black lead?
a) Charcoal
b) Diamond
c) Graphite
d) Fullerenes
Answer: c
Clarification: Graphite is also a crystalline form of allotropic carbon which is dark grey in color, it has hexagonal plates, the hybridization of carbon is sp² and it is a good conductor of heat and electricity due to the presence of electrons. It is known as a black lead and it is also a very good lubricant.

Chemistry Multiple Choice Questions on “Environmental Chemistry – Water Pollution”.

1. What is an easily identified source of pollution called as?
a) Specific source
b) Point source
c) Non-point source
d) Polluting source
Answer: b
Clarification: Easily identified source or place of pollution is called as point source. The examples of point sources are municipal and industrial discharge pipes where the pollutants enter the water-source as treated wastewater. A point source has a negligible extent, distinguishing it from other pollution source geometries.

2. Pick out the source of organic wastes pollutant from the following.
a) Industries
b) Erosion of soil by agriculture and strip mining
c) Water used for cooling in factories
d) Discharge from food processing factories
Answer: d
Clarification: Organic wastes, also known as biodegradable wastes, are natural wastes of plants and animals. The source of organic wastes include domestic sewage, animal excreta and waste, decaying animals and plants, as well as discharge from food processing factories. They can ultimately lead to harm when they use up the oxygen in the water body that they are dumped into.

3. Identify the bacteria not found in human excreta that causes gastrointestinal diseases.
a) Staphylococcus aureus
b) Escherichia coli
c) Streptococcus faecalis
d) Shigella
Answer: a
Clarification: Staphylococcus aureus is not found in human excreta. It is a round-shaped bacterium that is a member of the Firmicutes. It is mainly found on the upper respiratory tract and/or on skin. But they can also spread through the bloodstream and infect distant organs. Infections caused due to this bacterium can be transferred through the air, skin contact, etc.

4. Plants always take in carbon dioxide and release oxygen.
a) True
b) False
Answer: b
Clarification: Plants do not always take in carbon dioxide and release oxygen. Plants take in carbon dioxide during the day for the process of photosynthesis and release oxygen into the atmosphere. But at night, photosynthesis does not occur, due to the absence of sunlight, and therefore plants take in oxygen for breathing and give out carbon dioxide.

5. What is the amount of oxygen required by bacteria to break down organic matter present in certain volume of sample of water is called?
a) Bacterial oxidation
b) Bacterial decomposition
c) Biochemical oxygen demand
d) Biological oxygen demand
Answer: c
Clarification: The amount of oxygen required by bacteria to break down the organic matter present in a certain volume of a sample of water is called as Biochemical Oxygen Demand (BOD). The amount of BOD in water is a measure of the amount of organic material in the water, in terms of how much oxygen will be required to break it down biologically. Clean water has BOD value less than 5 ppm whereas highly polluted water has BOD value of 17 ppm or more.

6. What does the addition of phosphate fertilizers into water lead to?
a) Increased algae growth
b) Decreased algae growth
c) Increased growth of decomposers
d) Nutrient enrichment
Answer: d
Clarification: Addition of phosphate fertilizers into water bodies lead to nutrient enrichment. This condition is also known as eutrophication. When excess nutrients are formed, this, in turn, will lead to the growth of algae in the water body. These algae will consume the oxygen that is present in the water and thus, there will not be sufficient oxygen left for use of the aquatic organisms inhabiting the water body. As a result, death of these aquatic organisms will take place in large quantities. And therefore, leads to pollution.

7. What is the full form of PCB(in the context of chemistry)?
a) Printed Circuit Boards
b) Polychlorinated biphenyls
c) Polychemical biphenyls
d) Primary Chemical Bacteria
Answer: b
Clarification: The full form of PCB is Polychlorinated biphenyls. It is used as a cleansing solvent. PCBs are also suspected to be carcinogenic (can lead to cancer). Bacteria responsible for degrading biodegradable detergent feed on these and grow rapidly. While growing, they use up all the oxygen dissolved in water. Thus, the lack of oxygen kills all other forms of aquatic life such as fish and plants.

8. Water should be tested for fluoride ion concentration for drinking purposes.
a) True
b) False
Answer: a
Clarification: For drinking purposes, water should be tested for fluoride ion concentrations. Its deficiency in drinking water is harmful to man and causes diseases such as tooth decay. But, if present in higher concentrations, it causes brown mottling of teeth. It can also lead to harmful effects in bones.

9. The maximum limit of which of the following in drinking water should be 50 ppb?
a) Lead
b) Sulphate
c) Nitrate
d) Fluoride
Answer: a
Clarification: The maximum prescribed upper limit concentration of lead in drinking water is about 50 ppb. Drinking water gets contaminated with lead when lead pipes are used for the transportation of drinking water. Lead is a harmful substance and can cause damage in kidneys, liver, reproductive system, etc.

10. The excess of which ion in drinking water can lead to blue baby syndrome?
a) Aluminum ion
b) Copper ion
c) Sulphate ion
d) Nitrate ion
Answer: d
Clarification: Blue baby syndrome (methemoglobinemia) is a disease that is caused when the baby consumes drinking water which is rich in nitrates. It is caused when the maximum limit of nitrate in water, i.e. 50ppm, is crossed. When the baby drinks nitrate-rich water, then the nitrates get converted to nitrites and this will go and bind with the haemoglobin present in the blood, forming methemoglobin, which does not have the ability to carry oxygen. This is the reason for the blue color of the skin of the baby.

Chemistry Multiple Choice Questions on “Atomic Models”.

1. What is the absolute charge of a proton?
a) +1.602176×10^-27
b) –1.602176×10^-19
c) +1.602176×10^-19
d) –1.602176×10^-27
Answer: b
Clarification: According to the fundamental properties of particles, protons charge is +1.602176×10^-19C. It is a subatomic particle. Rutherford discovered protons. Its elementary charge is 1. Proton’s charge is positive.

2. Which of the following models are not the same as Thomson Model of Atom?
a) plum pudding model
b) watermelon model
c) raisin pudding model
d) nuclear model
Answer: d
Clarification: Thomson proposed a model of the atom, in which electrons are embedded to make it as the stable electrostatic arrangement and such that positive charge is equally distributed around a sphere. Mass is assumed to be equally distributed. So. it has different names like plum pudding, watermelon and raisin pudding model.

3. Elements do emit radiation on their own and this property is known as _____
a) Radioactivity
b) Refraction
c) Absorption
d) Adsorption
Answer: a
Clarification: Henri Becquerel discovered that elements emit radiation and termed this phenomenon as radioactivity. Later Curie on research found out about α-rays, β-rays and γ-rays. Later Rutherford concluded that α particles are helium nuclei.

4. Which of the following statements you think is wrong regarding α particle scattering effect?
a) α particles mostly move through the gold foil having zero deflection
b) A small fraction are deflected
c) One in Twenty Thousand turns 180°
d) The thickness of the gold foil is about 100μm
Answer: d
Clarification: In this effect, a thin foil (thickness 100nm) made up of gold and coated with fluorescent ZnS screen which is circular around it. α particles mostly move through the gold foil having zero deflection, a small fraction is deflected and one in twenty thousand turns 180°.

5. If the number of protons and neutrons of an element is 13 and 14 respectively, then what’s the atomic number(Z) and mass number(A)?
a) 13, 13
b) 13, 27
c) 14, 13
d) 27, 14
Answer: b
Clarification: For an element, Atomic number(Z) = number of protons in that atoms = numbers of electrons in that atom; Mass number = number of protons + number of neutrons. So Z = 13 and A = 13 + 14 = 27. Hence that element is Aluminium.

6. Which of the following is not an isotope of hydrogen?
a) protium
b) deuterium
c) tritium
d) helium
Answer: d
Clarification: Protium has only 1 proton, deuterium has one proton and 1 neutron whereas tritium has one proton and two neutrons. They are represented by ₁H¹, ₁D² and ₁T³. Helium has 2 protons and two neutrons, hence can’t consider as an isotope. Isotope means having the same number of protons but differ in the number of neutrons.

7. Chemical properties of an atom are dependent on a number of electrons in that particular atom.
a) True
b) False
Answer: a
Clarification: Yes, chemical properties of an atom is dependent on a number of electrons in that particular atom, which in turn is decided by the number of protons present in that atom. The number of neutrons has only a small effect on this.

8. Find out the number of neutrons, protons, and electrons of ₁₇Cl³⁷ respectively.
a) 20, 20, 17
b) 17, 17, 20
c) 20, 17, 17
d) 17, 17, 17
Answer: c
Clarification: An atom is written in the symbol ZXA. By comparing it to ₁₇Cl³⁷, we get a number of protons as 17 and mass number as 37. Mass number – proton number = neutron number. Number of neutrons is 37 – 17 = 20. No. of protons = No. of electrons = 17.

9. Pick out the isobar of ₁₈Ar⁴⁰.
a) ₁₂Mg²⁴
b) ₂₆Fe⁵⁸
c) ₁₉K⁴⁰
d) ₂₈Ni⁶⁴
Answer: c
Clarification: Isobar is a species of an element having the same mass number but a different atomic number. As per the above question, only ₁₉K⁴⁰ satisfies the conditions of ₁₈Ar⁴⁰ to be its isotope.

10. Gravitational force = Gm₁m₂/r².
a) True
b) False
Answer: a
Clarification: The formula of gravitational force is given by Gm₁m₂/r². Here G is the gravitational constant, while m₁ and m₂ are the masses and r is the distance between m₁ and m₂. This theory is formulated when classic mechanics is applied to it.

Chemistry Question Bank on “Molecular Structure – Hybridisation”.

1. Who introduced the concept of hybridization?
a) Pauling
b) London
c) Sidgwick
d) Alexander
Answer: a
Clarification: In order to explain the bonding and shapes of every polyatomic atomic molecule like methane, carbon tetrachloride, water, boron trifluoride, etc, Pauling put-forth the concept of hybridization.

2. The phenomenon of forming completely new atomic orbitals by intermixing them is known as ___________
a) Allocation
b) Hybridization
c) Chemical bond formation
d) Electron configuration
Answer: b
Clarification: The exact meaning of hybridization is the intermixing of different orbitals in order to form a new set of equivalent orbitals otherwise known as hybridized orbitals. These hybrid orbitals are used in bond formation.

3. The orbitals that are resulted from sp hybridization have _______% s-character and ________% p-character.
a) 25, 75
b) 75, 25
c) 20, 80
d) 50, 50
Answer: d
Clarification: When one s-orbital and p-orbital undergo hybridization, 2 sp orbitals are formed. One sp-orbital has 50% s-character and 50% p-character. They possess linear geometry and it’s also called diagonal hybridization.

4. What type of hybridization does a BCl₃ molecule undergo?
a) sp
b) sp²
c) sp³
d) sp³d
Answer: b
Clarification: In the BCl₃ molecule, one s-orbital and two p-orbitals intermix and form three equivalent hybrid orbits. Therefore it undergoes sp² hybridization and forms trigonal planar shape, like B in the center and Cl in the 3 corners.

5. What is the bond angle of H-C-H in methane molecule?
a) 104.5°
b) 109.5°
c) 108°
d) 120°
Answer: b
Clarification: The molecule of methane i.e. CH₄ had undergone sp³ hybridization (1 s-orbital and 3 p-orbitals combine to give 4 sp³ orbitals). It exhibits tetrahedral geometry. In tetrahedral geometry, the angle between the bonds of corner atoms and the central atom is 109.5°.

6. What do you think is the number of sigma bonds in an ethene molecule?
a) 6
b) 7
c) 4
d) 5
Answer: d
Clarification: The formula of ethene molecule is C₂H₄. There is one sigma bond between two carbon atoms and 2 sigma bonds between each of the carbon and the hydrogens. So in total, it’s five (one pi-bond is present between the 2 carbon atoms).

7. Mention the types of orbitals that undergo hybridization in order to get octahedral geometry?
a) s-orbital only
b) s-orbital and p-orbital
c) s-orbital, p-orbital, and d-orbital
d) d-orbital and p-orbital
Answer: c
Clarification: Octahedral geometry is possible when the atomic orbitals under undergoing sp³d² or d²sp³ hydration only. So it involves one s-orbital, three p-orbitals, and two d-orbitals. An example of this is SF₆.

8. What is the geometry of PCl₅ molecule?
a) Square pyramidal
b) V-shape
c) Trigonal bipyramidal
d) Tetrahedral
Answer: c
Clarification: As the PCl₅ molecule undergoes sp³d hybridization, it posses the geometry the trigonal bipyramidal. In the shape, the central atom is Phosphorous and the atoms at the five corners are Chlorine.

9. The orbitals formed after hybridization have equal energy.
a) True
b) False
Answer: a
Clarification: The hybridization is the intermixing of different orbitals in order to form a new set of equivalent orbitals otherwise known as hybrid orbitals. All the hybrid orbitals those have undergone the same hybridization have the same amount of energy.

10. Which of the following statement is true regarding hybrid orbitals?
a) The amount of orbitals formed after the hybridization is not equal to the number of orbitals before hybridization
b) The hybrid orbitals don’t have equal energy
c) They can form more stable bonds than the pure orbitals
d) Hybridization doesn’t indicate geometry
Answer: c
Clarification: The true statements of the incorrect ones are the number of orbitals formed after the hybridization is equal to the number of orbitals before hybridization, the hybrid orbitals have equal energy and the hybridization indicates geometry.

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