Category: Class 12 Chemistry Objective Questions

Chemistry Question Papers for IIT JEE Exam on “Chemicals in Food”.

1. Which of the following chemicals are added to increase the shelf-life of foods?
a) Food colour
b) Sweeteners
c) Artificial flavours
d) Antioxidants
Answer: d
Clarification: Chemicals are added to food for improving their aesthetic, to increase their shelf-life or to add nutritive value. Food colours, flavours and sweeteners simply enhance the appearance and taste of food. Antioxidants are used for preservation.

2. Which of the following artificial sweeteners can be only used in soft drinks?
a) Aspartame
b) Alitame
c) Sucralose
d) Saccharin
Answer: a
Clarification: Aspartame is an artificial sweetening agent which is unstable at higher temperatures. It is a compound formed from aspartic acid and phenylalanine. It is 100 times as sweet as cane sugar.

3. Alitame is ______ times sweeter than cane sugar.
a) 50
b) 100
c) 600
d) 2000
Answer: d
Clarification: Alitame is a compound consisting of one hydroxy group, three keto groups and a tetra-methyl sulphur containing cyclic group. It is a very strong sweetener and provides uncontrollable sweetness to food.

4. Which of the following is not a preservative?
a) Dulcin
b) Potassium metasulphite
c) Sodium benzoate
d) Sorbic acid salts
Answer: a
Clarification: Preservatives are chemicals that are added to food to prevent their spoilage and preserve their nutritive value and taste. Salt, sugar and oils are the most common examples. Potassium metasulphite is used in jams. Dulcin is an artificial sweeter.

5. Which of the following is not an antioxidant?
a) BHT
b) BHA
c) Saccharin
d) Sulphur dioxide
Answer: c
Clarification: Antioxidants prevent food spoilage by itself reacting with oxygen and protecting the food from oxidation. Butylated hydroxy toluene and butylated hydroxy anisole increase the shelf lives of food like butter. SO₂ is also used in wines, fruits and sugar syrups for preservation.

Chemistry Question Papers for IIT JEE Exam,

Chemistry Multiple Choice Questions on “Amorphous and Crystalline Solids”.

1. In polar molecular solids, the molecules are held together by ________
a) dipole-dipole interactions
b) dispersion forces
c) hydrogen bonds
d) covalent bonds
Answer: a
Clarification: Molecular solids are solids that are collections of molecules held together by intermolecular forces. In polar molecules such as HCl, So₂, etc., the molecules are held together by dipole-dipole interactions.

2. Diamond is an example of _______
a) solid with hydrogen bonding
b) electrovalent solid
c) covalent solid
d) glass
Answer: c
Clarification: The solids in which constituent particles are attached to each other by covalent bonds are called covalent solids. Diamond, graphite, silicon, SiC, AIN, quartz are examples of covalent solids.

3. Silicon is found in nature in the forms of ________
a) body-centered cubic structure
b) hexagonal-closed packed structure
c) network solid
d) face-centered cubic structure
Answer: c
Clarification: Silicon due to its catenation property form network solid. Catenation is the ability of an atom to form bonds with other atoms of the same element. The compounds of silicon are reactive and not stable.

4. Which one of the following are the dimensions of cubic crystal?
a) a =b ≠ c
b) a = b = c and α = β ≠ γ = 90
c) a = b = c and α = β = γ = 90
d) a ≠ b = c and α = β ≠ γ = 90
Answer: c
Clarification: The dimensions of a cubic crystals are a = b = c, α = β = γ = 90.

5. Which of the following is not a crystal system?
a) Cubic
b) Trigonal
c) Triclinic
d) Hexaclinic
Answer: d
Clarification: Hexaclinic is not a crystal system. Their crystal system are cubic, tetragonal, rhombohedral or trigonal, orthorhombic or rhombic, monoclinic, triclinic and hexagonal.

6. In face-centred cubic cell, a unit cell is shared equally by __________
a) four unit cells
b) two unit cells
c) one unit cell
d) six unit cells
Answer: d
Clarification: The unit cell in which atoms are present at corners as well as faces of unit cell is known as face-centred cubic unit cell. In face-centred cubic cell, a unit cell is shared equally by six unit cells.

7. The unit cell with a≠b≠c and α=β=γ=90 refers to __________ crystal system.
a) hexagonal
b) trigonal
c) triclinic
d) orthorhombic
Answer: d
Clarification: In orthorhombic crystal system, all three axes are unequal in length and all are perpendicular to one another. It is also called as rhombic crystal system. Topaz, barite are some examples of orthorhombic crystals.

8. Which is the most unsymmetrical crystal system?
a) Triclinic crystal system
b) Cubic crystal system
c) Hexagonal crystal system
d) Trigonal crystal system
Answer: a
Clarification: Most unsymmetrical crystal system is triclinic in which all three axes are unequal in length none is perpendicular to another. Triclinic unit cells has the least symmetrical shape of all unit cells. Turquoise is an example of triclinic crystal.

9. In the simple cubic cell, each corner atom is shared by __________
a) eight unit cells
b) one unit cell
c) two unit cells
d) six unit cells
Answer: a
Clarification: The unit cell in which the constituent atoms are present only at the corner is known as simple cubic cell. It is also referred to as a primitive cubic cell. In the simple cubic cell, each corner atom is shared by eight different unit cells.

10. The points which shows the position of atoms in crystal are called as _________
a) crystal lattice
b) crystal parameters
c) bravais lattice
d) lattice point
Answer: d
Clarification: The point at which the atoms may be present on the unit cell is termed as lattice point. It shows the position of atoms in crystal.

11. The unit cell with a≠b≠c and α=γ=90, β≠90 refers to __________crystal system.
a) cubic
b) tetragonal
c) monoclinic
d) triclinic
Answer: c
Clarification: In monoclinic crystal system, all the three axes are unequal in length and two axes are perpendicular to each other. Gypsum and borax are examples of monoclinic crystals.

12. Which type of solid crystals will conduct heat and electricity?
a) Ionic
b) Covalent
c) Molecular
d) Metallic
Answer: d
Clarification: Metallic crystals consist of metal cations surrounded by a sea of mobile valence electrons. These electrons are capable of moving through the entire crystal. The metallic crystals conduct heat and electricity due to the presence of these mobile electrons in them.

13. Which is not a characteristic of crystalline solids?
a) They undergo a clean cleavage
b) They are true solids
c) They are isotropic
d) They have sharp melting points
View Answer

Answer: c
Clarification: Amorphous solids are isotropic that is they have identical properties in all directions, whereas crystalline solids are anisotropic that is they have different properties in different directions.

14. Which of the following is a characteristic of amorphous solid?
a) They are true solids
b) They have sharp melting points
c) They undergo clear cleavage
d) They are isotropic
Answer: d
Clarification: Amorphous solids are isotropic that is they have identical properties in all directions. The remaining options are the characteristics of crystalline solids.

15. Solids are classified as ___________
a) crystalline and ionic solids
b) metallic and amorphous solids
c) molecular and covalent solids
d) crystalline and amorphous solids
Answer: d
Clarification: Based on their crystal structures, solids are classified as crystalline and amorphous solids. In crystalline solids, the constituent particles are arranged in a regular manner. In amorphous solids, the constituent particles are not arranged in any regular manner.

16. Quartz is an example of ___________
a) molecular solids
b) ionic solids
c) covalent solids
d) metallic solids
Answer: c
Clarification: Quartz is a common example of covalent solids. In covalent solids, the constituent particles are attached to each other by covalent bonds. Diamond, graphite, silicon are other examples of covalent solids.

17. Solid carbon dioxide is an example of _________
a) metallic crystal
b) covalent crystal
c) ionic crystal
d) molecular crystal
Answer: d
Clarification: Solid CO₂ is an example of molecular crystal. These solids have molecules as their constituent particles. These solids may be bonded by vander waals’ forces or by dipole-dipole attraction or by strong hydrogen bonds. H₂, Cl₂, I₂ are some examples of molecular solids.

Chemistry Online Quiz for Schools on “Colligative Properties and Determination of Molar Mass – 2”.

1. Why is ‘raising of viscosity’ of a solution after addition of solute, not considered to be a colligative property?
a) The resultant viscosity depends on the nature of the solute
b) The resultant viscosity depends on the amount of solute
c) The resultant viscosity depends on the nature of solvent
d) The resultant viscosity depends on the amount of solvent
Answer: a
Clarification: A colligative property is identified by the fact that it has no dependence on the nature of the particles of solute. However, in the case of viscosity it really depends on the solute that is added to the solvent. Thus, the change in viscosity after addition of a non-volatile solute cannot be considered to be a colligative property.

2. At 70°C the vapor pressure of pure water is 31 kPa. Which of the following is most likely the vapor pressure of a 2.0 molal aq. glucose solution at 70°C?
a) 30.001 kPa
b) 29.915 kPa
c) 28.226 kPa
d) 32.392 kPa
Answer: b
Clarification: Given, P⁰_water = 31 kPa
Concentration of solution, c = 2 molal = 2 moles of glucose/kg of water
From law of relative lowering of vapor pressure, ΔP/P⁰ = X₂, where X₂ is the mole fraction of glucose in the solution.
Mass of water = 1 kg = 1000 g
Molecular weight of water = 18 g/mole
Moles of water = 1000/18 = 55.556 moles
X₂ = 2/(2 + 55.556) = 0.035
ΔP = 31 kPa x 0.035 = 1.085 kPa
Final pressure = 31 kPa – 1.085 kPa = 29.915 kPa.

3. 117 g of NaCl is added to 222 g of water in a saucepan. At what does temperature does water boil at 101.325 kPa? Ebullioscopy constant for water = 0.52 K kg mol^-1 and b.p. = 100°C
a) 98.3°C
b) 102.8°C
c) 104.7°C
d) 101.5°C
Answer: c
Clarification: Given,
Weight of solvent, w₁ = 222 g
Weight of solute, w₂ = 117 g
K_b = 0.53 K kg mol^-1
Now, addition of a non-volatile solute causes elevation in boiling point, ΔT_b
ΔT_b = (k_b x 1000 x w₂)/(M₂ x w₁)
On substituting, ΔT_b = (0.52 x 1000 x 117)/(58.5 x 222) = 4.7°C
New boiling temperature = 100 + 4.7 = 104.7°C.

4. Boiling point of chloroform is 61°C. After addition of 5.0 g of a non-volatile solute to 20 g chloroform boils at 64.63°C. If k_b = 3.63 K kg mol^-1, what is the molecular weight of the solute?
a) 320 g/mol
b) 100 g/mol
c) 400 g/mol
d) 250 g/mol
Answer: d
Clarification: Given,
b.p. of chloroform = 61°C
New b.p. after addition = 64.63°C
Mass of solute, w₂ = 5.0 g
Mass of solvent, w₁ = 20 g
K_b = 3.63 K kg mol^-1
From these, ∆T_b = 64.63 – 61 = 3.63°C
Using ΔT_b = (k_b x 1000 x w₂)/(M₂ x w₁)
M₂ = (k_b x 1000 x w₂)/(ΔT_b x w₁)
M₂ = (3.63 x 1000 x 5)/(3.63 x 20) = 250 g/mol.

5. Pure CS₂ melts at -112°C. 228 grams of propylene glycol crystals is mixed with 500 grams of CS₂. If k_f of CS₂ = -3.83 K kg mol^-1 what is the depression in freezing point?
a) -23°C
b) -135°C
c) -20°C
d) -100°C
Answer: a
Clarification: Given,
k_f = -3.83 k kg mol^-1
Mass of solute, w₂ = 228 g
Mass of solvent, w₁ = 500 g
Molar mass of solute, M₂ = 76 g/mole
Moles of solute = w₂/M₂ = 228/76 = 3 moles
Molality of the solution, m = Number of moles of solute/mass of solvent (kg)
m = 3 moles/0.5 kg = 6 molal
We know, ΔT_f = k_f x m
ΔT_f = -3.83 x 6 = -23°C.

6. What are colligative properties useful for?
a) Determining boiling and melting temperature
b) Determining molar mass
c) Determining equivalent weight
d) Determining van’t Hoff factor
Answer: b
Clarification: Colligative properties serve the purpose for determining molar masses of unknown compounds. Colligative properties are not used to determine boiling and melting temperatures as it would result in an incorrect value upon the addition of a solute. Equivalent weight can only be determined if the molar mass is known and the van’t Hoff factor is determined in a similar manner.

7. A pair of solution bears the same osmotic pressure. What is this pair of solutions called?
a) Hypertonic
b) Hypotonic
c) Isotonic
d) Osmolarity
Answer: c
Clarification: Two solutions having the same osmotic pressure at a given temperature are called isotonic solutions. Hypertonic solutions are those in which the concentration of solute outside the membrane and a lesser concentration within the membrane. Osmolarity is a type of concentration expressed in number of solute particles per liter.

8. A cell with lots of salt inside it is placed in a vessel containing just water. Which process takes place?
a) Dialysis
b) Filtration
c) Shriveling
d) Osmosis
Answer: d
Clarification: Osmosis is a mass transfer process due to which water molecules move from a region of higher water potential to lower water potential down the potential gradient. Dialysis and filtration are processes using the concept of diffusion of impurities. Shriveling is the shrinking of a cell. In this case, the cell swells up.

9. What is a necessary condition for osmosis to take place?
a) Semi-permeable membrane
b) Same concentration of solvent
c) High temperature
d) Pressure greater than osmotic pressure
Answer: a
Clarification: A semi permeable membrane is a must condition since it facilitates the blocking of solute particles from diffusing through and allows only water molecules to pass through. Obviously, water is the solvent in osmosis hence the concentration of solvent cannot be same if osmosis has to occur. If pressure greater than osmotic pressure is applied, reverse osmosis takes place. Meaning, water molecules will flow from region of lower water potential to higher water potential.

10. Which is the most appropriate method for determining the molar masses of biomolecules?
a) Relative lowering of vapor pressure
b) Elevation of boiling point
c) Depression in freezing point
d) Osmosis
Answer: d
Clarification: Osmotic pressure method has the greatest advantage over other methods that even for very dilute concentrations it gives a large magnitude. This would not be true in case other methods. It is highly useful for biomolecules since they are unstable at extremely high and low temperatures thus eradicating the method using boiling and freezing points.

Chemistry Online Quiz for Schools,

Chemistry Multiple Choice Questions on “Surface Chemistry – Adsorption”.

1. A finely divided substance is more effective as an adsorbent.
a) True
b) False
Answer: a
Clarification: Adsorption is a surface phenomenon. It is dependent on the amount of the adsorbent exposed to the adsorbate. A finely divided substance provides a large surface area and hence, provides more sites where adsorption can take place.

2. What is the process called when the molecules of a substance are retained at the surface of a solid or a liquid?
a) Absorption
b) Adsorption
c) Sorption
d) Desorption
Answer: b
Clarification: Adsorption is the process which involves the accumulation of the molecules of a substance in higher concentration on the surface of a solid or a liquid. For example, gasses are adsorbed on the surface of charcoal.

3. Which of the following forces is involved in physical adsorption?
a) Gravitational force
b) Magnetic force
c) Van der Waals force
d) Electromagnetic force
Answer: c
Clarification: In physical adsorption, the molecules of the adsorbate stick to the surface of the adsorbent due to very weak forces which is known as Van der Waals force. Van der Waals force is similar to the forces that cause condensation of gas into liquid.

4. In physisorption, the adsorbent does not show specificity towards a particular gas.
a) True
b) False
Answer: a
Clarification: In physisorption, there is no chemical bond between the adsorbent and adsorbate. They are held together by Van der Waals forces. Since Van der Waals forces are universal and almost same for all gases, the adsorbent does not show specificity to a particular gas.

5. Which of the following statements is true with respect to the extent of physisorption?
a) Increases with increase in temperature
b) Decreases with increase in surface area
c) Decreases with increase in the strength of Van der Waals forces
d) Decreases with increase in temperature
Answer: d
Clarification: Physisorption is an exothermic process. According to Le-Chatelier’s principle, an exothermic reaction is favoured by a decrease in temperature. Therefore, the extent of physisorption decreases on increasing temperature.

6. Which of the following can result in a transition from physisorption to chemisorption?
a) Decrease in temperature
b) Increase in temperature
c) Decrease in pressure
d) Increase in surface area
Answer: b
Clarification: Physisorption occurs due to Van der Waals forces. On increasing the temperature, the adsorbate can split into atoms and form chemical bonds with the adsorbent and hence, cause chemisorption.

7. Which of the following statements is incorrect with respect to physisorption?
a) It is reversible
b) It is spontaneous
c) ΔH d) ΔS > 0
Answer: d
Clarification: Physisorption is reversible as the molecules of the adsorbate are held to the adsorbent by weak Van der Waals forces which can be broken easily. Physisorption is exothermic and so, ΔH is negative. Adsorption is a spontaneous process. In adsorption, the movement of the adsorbed molecule is restricted. As a result the entropy change (ΔS) is negative.

8. Which of the following statements is true with respect to the types of adsorption?
a) Chemisorption is stronger than physisorption
b) Physisorption is stronger than chemisorption
c) They are both equal
d) They cannot be compared
Answer: a
Clarification: Chemisorption is stronger than physisorption. Chemisorption involves the forming of a chemical bond between the adsorbent and the adsorbate whereas in physisorption, the molecules are held together by weak Van der Waal’s forces. Therefore, chemisorption is stronger.

9. Which of the following is an example of sorption?
a) Sponge in water
b) Cotton dipped in ink
c) Water on silica gel
d) Oxygen on metal surface
Answer: b
Clarification: Sorption refers to the process where adsorption and absorption occur at the same time. Cotton dipped in ink is one of the cases where both adsorption and absorption, that is, sorption occurs.

10. Which of the following statements is not true with respect to chemisorption?
a) Depends on nature of adsorbate and adsorbent
b) Has a large heat of adsorption
c) Forms a unimolecular layer
d) Occurs at low temperature
Answer: d
Clarification: Chemisorption is a kind of adsorption that involves a chemical reaction between the adsorbent and adsorbate, resulting in the formation of a chemical bond between the two. Since a bond is to be formed, chemisorption is highly dependent on the reactants(adsorbate and adsorbent) and has a large heat of adsorption. Also, since it involves bond formation, it cannot be multi-layered. Chemisorption is favoured to occur at high temperature.

Chemistry Multiple Choice Questions on “P-Block Elements – Ammonia”.

1. What is the chemical formula of ammonia?
a) NH₂
b) NH₃
c) NH₄⁺
d) NH₅
View Answer

Answer: a
Clarification: Ammonia is a tri-hydride of nitrogen. It is a colorless gas with a highly pungent smell that causes nasal irritation. It is the most stable hydride of any element in group 15.

2. What kind of smell is ammonia recognized by?
a) Acidic
b) Sweet
c) Rotten
d) Pungent

Answer: d
Clarification: Ammonia has a highly pungent smell. With a sharp, pinching smell, it causes severe irritation in the nose and throat. This pungent smell of ammonia is used as a means to identify the presence of ammonium cation, NH₄⁺ in salt analysis.

3. How many unshared pair of electrons does an ammonia molecule have?
a) 1
b) 2
c) 3
d) 4
Answer: a
Clarification: The nitrogen atom in NH₃ (ammonia) bears one lone pair of electron. Each single electron of hydrogen is bonded to the nitrogen atom. Three of out five electrons of nitrogen are involved in bonding whereas the unbounded two electrons make up the single unshared pair of electron.

4. What happens when sodium is put in a solution of ammonia?
a) It generates a lot of heat
b) It does not dissolve
c) It produces deep blue color
d) Ammonia liquid evaporates due to heat
Answer: c
Clarification: When sodium is introduced to liquid ammonia, it separates into sodium ion and a single electron (Na → Na⁺ + e^–). The single electron produces the deep blue color due to solvation effect producing e^–[NH₃]_n.

5. What is one method of qualitatively analyzing a given salt for presence of ammonia?
a) Solution turns blue litmus red
b) Heating the salt causing decrepitation
c) Using a reagent to obtain dirty brown precipitate
d) Addition of NaOH causing white gelatinous precipitate
Answer: c
Clarification: Typically, Nessler’s reagent is used to test for ammonia. Nessler’s reagent is an alkaline solution of potassium tetraiodomercurate (II). When it combines with ammonia it gives dirty brown precipitate due to the formation of [OHg₂.NH₂]I. Another method is to add a strong base and heat the mixture. The gas given off is pungent and turns red litmus blue.

6. What is the most acidic of all?
a) NH₃
b) NaOH
c) KOH
d) Alkaline KMnO₄
Answer: a
Clarification: In the listed options, except ammonia, every other compound is a strong base which automatically makes ammonia the most acidic relative to the mentioned compounds. Although it is a weak base, compared to NaOH, KOH and alkaline KMnO₄ it is the most acidic amongst the four options.

7. In the Haber-Bosch process, what is formed by the reaction of natural gas and steam?
a) Ammonia
b) Nitrogen
c) Oxygen
d) Hydrogen
View Answer

Answer: d
Clarification: The reaction of natural gas and steam is known as the steam reformation of methane. It is an utmost important step in the Bosch-Haber (industrial process to produce ammonia), which produces hydrogen gas, H₂, one of the two reactants alongside nitrogen to produce ammonia in presence of iron catalyst.

8. Which of the following conditions would improve the yield of ammonia production from Bosch-Haber process?
a) High temperature, high pressure
b) High temperature, low pressure
c) Low temperature, low pressure
d) Low temperature, high pressure
Answer: d
Clarification: Following the Le Chatelier’s principle, since the forward reaction is exothermic (i.e. N₂ + 3H₂ → 2NH₃), low temperatures would increase the rate of reaction in turn producing more ammonia. In addition to this, since the total number of molecules on the product side lesser, high pressures will increase the rate of reaction.

9. Nitrogen in plants is taken in what form?
a) Ammonia
b) Amide
c) Nitrate
d) Nitrite
Answer: c
Clarification: Plants take up nitrogen predominantly in the form of nitrate ions, along side ammonium ions. This is made available to them through fertilizers, whose typical examples usually include Ammonium Phosphate, calcium ammonium nitrate.

Chemistry Multiple Choice Questions on “P-Block Elements – Chlorine”.

1. What is the molecular mass of chlorine?
a) 71.0 kg/kmole
b) 35.5 g/kmole
c) 71.0 g/kmole
d) 35.5 kg/mole
Answer: a
Clarification: In the periodic table, the atomic mass of chlorine atom is 35.5 AMU. Since chlorine exists in diatomic form, the molecular mass = 35.5g/mole x 2 = 71.0 g/mole. On multiplying and dividing by 1000, 71.0 kg/kmole.

2. Which of the following would instantly react with chlorine?
a) Copper
b) Magnesium
c) Iron
d) Aluminum
Answer: b
Clarification: Out of the four metals given, magnesium will readily lose electrons due to its relatively higher reactivity. Copper and iron are not affected by gaseous or liquid chlorine. Lastly, aluminum forms a tough, passive oxide layer which prevents it from reacting with external reagents.

3. What is the color of chlorine?
a) Yellow grey
b) Greenish brown
c) Green yellow
d) Yellow
Answer: c
Clarification: Every halogen bears a characteristic color which is used in identifying it. Fluorine is a bright yellow gas. Chlorine is greenish yellow, followed by bromine which is brown and iodine which is purple/violet. Astatine is a black solid which is radioactive in nature.

4. When excess chlorine reacts with methane in presence of sunlight, which is the major product?
a) Refrigerant – 40
b) Methylene chloride
c) Chloroform
d) Carbon tetrachloride
Answer: d
Clarification: In presence of sunlight, a free radical substitution reaction takes place between the reacting methane and chlorine molecules where in each elementary reaction a hydrogen atom is replaced by a chlorine atom in the new product. First, methane converts to 1-chloromethane which in turn produces dichloromethane followed by tri-chloromethane and tetra-chloromethane, respectively.

5. Which of the following is a suitable test to identify presence of chlorine atoms or ions?
a) Acidify the given compound and add silver nitrate
b) Add silver nitrate followed by warming the solution
c) Heat the compound strongly
d) Smell the compound
Answer: a
Clarification: The standard, universal qualitative test for detecting presence of chloride is carried out by acidifying the solution and then adding silver nitrate. If chloride ions are present, a thick white ppt. is produced.

6. Why is chlorine bubbled through water during the latter’s treatment?
a) To remove foul odor
b) To kill microorganisms
c) To improve taste
d) To remove hardness
Answer: b
Clarification: Chlorine is a very popular disinfecting agent and is widely used in containers to kill microorganisms. In water treatment plants, chlorine gas may be bubbled through to remove trace quantities of microorganisms.

7. What is the electronic configuration of chloride?
a) 1s²2s²2p⁶3s²3p⁵
b) 1s²2s²2p⁶3s²3p⁶
c) 1s²2s²2p⁵
d) [Ar]4s²4p³
View Answer

Answer: b
Clarification: Chlorine has the atomic number 17. However, chloride has 18 electrons. Consequently, it attains the electronic configuration of argon i.e.1s²2s²2p⁶3s²3p⁶.

8. How is chlorine gas manufactured industrially?
a) Deacon process
b) Ostwald process
c) Chlor-alkali process
d) Haber process
Answer: c
Clarification: Although Deacon process involves release of chlorine gas as a byproduct, the chief purpose of the deacon process is used to manufacture alkalis. Chlorine is best produced by the chloralkali process, which is the electrolysis of brine, producing hydrogen and chlorine gases as by products.

9. Hydrogen chloride as an acid is much stronger than hydrogen fluoride under the same conditions. True or False?
a) True
b) False
Answer: a
Clarification: Fluorine atom is extremely small compared to chlorine. This means that the bond of H – F is much more polar than that of H – Cl, causing the H atom to be more tightly bonded in case of H – F than in H – Cl. Since hydrogen chloride is able to release the H+ much easily, the latter is a stronger acid.

10. Which of the following is a result of bubbling hydrogen chloride gas through gas?
a) H^– + Cl^–
b) H⁺ + Cl^2-
c) H₃O⁺ + Cl^–
d) H⁺ + Cl^–
Answer: c
Clarification: The hydrogen chloride molecule, HCl dissociates in water giving rise to one hydrogen ion and a chloride ion. The extremely small hydrogen ion bearing the positive charge is instantly attracted by the unshared pair of electrons of the oxygen atom in water molecules, consequently giving rise to the hydronium ion, H₃O⁺.

11. What will be the result of subjecting a blue litmus to chlorine gas?
a) Turn to red only
b) Remain blue
c) Turn to white finally
d) Turn white in the first go
Answer: c
Clarification: Chlorine bears bleaching properties. When blue litmus is subjected to chlorine gas, it first turns red (due to the acidic nature) then it turns white (due to chlorine’s ability to bleach materials).

12. To which group does chlorine element belong?
a) Halides
b) Pre inert
c) Chalcogens
d) Halogens
Answer: d
Clarification: Fluorine, chlorine, bromine, iodine and astatine belong to Group 17 of the periodic table. This group is commonly named as Halogens because of their ability to produce salt on reacting with metals.

13. Which of the following is the displays the most basic nature in water?
a) Fluoride
b) Chloride
c) Bromide
d) Iodide
Answer: a
Clarification: The fluoride ion is actually not an oxidizing agent. Due to its high electronegativity and high reactivity, it converts water to form hydroxide ions. The reaction is given by 2F^– + H₂O → H – F – H^– + OH^–.

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