Important Compounds and Its Uses MCQ Quiz - Objective Question with Answer for Important Compounds and Its Uses - Download Free PDF

CONCEPT:

Chemical Names and Their Formulas

• Chemicals are often referred to by their common names, but they also have specific chemical formulas that represent their composition.
• Matching chemical names with their correct formulas is essential for understanding their properties and applications.
• Below are common examples:
  • Washing soda: Na₂CO₃·10H₂O (Sodium carbonate decahydrate)
  • Baking soda: NaHCO₃ (Sodium bicarbonate)
  • Bleaching powder: CaOCl₂ (Calcium oxychloride)
  • Gypsum: CaSO₄·2H₂O (Calcium sulfate dihydrate)

Therefore, the correct answer (a) - (3) , (b) - (2) , (c) - (1) , (d) - (4) 

The correct answer is Mg₃(PO₄)₂.

Key Points

• The compound Mg₃(PO₄)₂ is formed due to the combination of magnesium ions (Mg²⁺) and phosphate ions (PO₄^3-) in a ratio of 3:2 to maintain charge balance.
• Magnesium has a charge of +2, while phosphate has a charge of -3. To neutralize the charges, three magnesium ions combine with two phosphate ions.
• The formula Mg₃(PO₄)₂ represents magnesium phosphate, a common ionic compound.
• Ionic compounds are formed by the electrostatic attraction between positively charged cations and negatively charged anions.
• This compound is often used in fertilizers and various industrial applications due to its phosphate content.

Additional Information

• Magnesium (Mg):
  • Magnesium is an alkaline earth metal with an atomic number of 12.
  • It commonly forms divalent cations (Mg²⁺) in chemical reactions.
  • It is essential for biological processes like enzyme activation and photosynthesis.
• Phosphate (PO₄^3-):
  • Phosphate is a polyatomic ion consisting of one phosphorus atom bonded to four oxygen atoms.
  • It carries a -3 charge and is widely found in biological systems and minerals.
  • Phosphates are critical for energy storage and transfer in cells (e.g., ATP).
• Ionic Compounds:
  • Ionic compounds are formed by the transfer of electrons, leading to cations and anions.
  • They exhibit high melting and boiling points due to strong ionic bonds.
  • Most ionic compounds dissolve in water, producing electrolyte solutions.
• Charge Balance in Ionic Compounds:
  • The ratio of ions in an ionic compound is determined by their charges to ensure overall neutrality.
  • For Mg₃(PO₄)₂, three Mg²⁺ ions neutralize the charge of two PO₄^3- ions.
  • This balance is a fundamental principle in chemical formula writing.

The correct answer is Magnesium hydroxide.

Key Points

• Milk of Magnesia is primarily composed of Magnesium hydroxide, a compound with the formula Mg(OH)₂.
• It is commonly used as an antacid to neutralize stomach acid and relieve indigestion, heartburn, and acid reflux.
• Magnesium hydroxide also acts as an osmotic laxative, drawing water into the intestines and facilitating bowel movements.
• The suspension is white in color and is popularly prescribed for constipation and gastrointestinal discomfort.
• Its action is mild and generally safe for most individuals, making it a widely used over-the-counter medication for digestive issues.

Additional Information

• Magnesium hydroxide:
  • It is a chemical compound classified as a base and sparingly soluble in water.
  • Used not only in medicine but also in industrial applications, such as wastewater treatment to neutralize acids.
• Mechanism of laxative action:
  • Magnesium hydroxide increases the water content in the intestines, softening stool and easing its passage.
  • It is particularly effective in treating short-term constipation.
• Precautions:
  • Prolonged or excessive use can lead to imbalances in electrolytes, particularly magnesium levels.
  • Not recommended for individuals with kidney disorders, as magnesium can accumulate in the body.
• Other uses:
  • Magnesium hydroxide is also employed as a flame retardant and in the manufacture of fertilizers.
  • Its antacid properties make it effective for relieving hyperacidity and associated symptoms.

EXPLANATION

Plaster of Paris (POP)

• Plaster of Paris is a material widely used for making casts, molds, and sculptures.
• It is produced by heating gypsum (calcium sulfate dihydrate) to remove part of its water content.
• The chemical formula of gypsum is CaSO₄·2H₂O (calcium sulfate dihydrate).
• When gypsum is heated to about 150°C, it loses water molecules and converts into calcium sulfate hemihydrate (Plaster of Paris) with the formula CaSO₄·½H₂O.

​Therefore the correct formula of plaster of pairs is \(\rm CaSO_4.\frac{1}{2}H_2O\)

The correct answer is NO2.

Key Points

• Supersonic aircrafts release nitrogen oxides (NOx), particularly NO2, into the stratosphere.
• These emissions occur at high altitudes where supersonic aircrafts operate, typically between 10 km and 20 km above the Earth's surface.
• NO2 is a significant contributor to the depletion of the ozone layer.
• The presence of NO2 in the stratosphere leads to complex chemical reactions that break down ozone (O3) molecules.
• Regulations and technological advancements are continuously being developed to mitigate the impact of NO2 emissions from supersonic aircrafts.

Additional Information

• Stratosphere
  • The stratosphere is the second major layer of Earth's atmosphere, just above the troposphere and below the mesosphere.
  • It extends from about 10 km to 50 km above the Earth's surface.
  • This layer contains the ozone layer, which absorbs and scatters ultraviolet solar radiation.
• Ozone Layer
  • The ozone layer is a region of Earth's stratosphere that contains a high concentration of ozone (O3) molecules.
  • It protects living organisms by blocking most of the sun's harmful ultraviolet (UV) radiation.
  • Depletion of the ozone layer leads to increased UV radiation reaching the Earth's surface, causing health and environmental issues.
• Supersonic Aircraft
  • Supersonic aircraft are designed to fly faster than the speed of sound (Mach 1).
  • Examples include military jets like the F-22 Raptor and the retired Concorde commercial airliner.
  • Supersonic flight poses unique challenges, including high fuel consumption and environmental impacts such as NOx emissions.
• Nitrogen Oxides (NOx)
  • NOx is a generic term for the nitrogen oxides that are most relevant for air pollution, including NO and NO2.
  • They are produced from the reaction of nitrogen and oxygen gases in the air during combustion, especially at high temperatures.
  • NOx emissions contribute to smog and acid rain and have harmful effects on human health and the environment.

The correct answer is NO2.

Key Points

• Supersonic aircrafts release nitrogen oxides (NOx), particularly NO2, into the stratosphere.
• These emissions occur at high altitudes where supersonic aircrafts operate, typically between 10 km and 20 km above the Earth's surface.
• NO2 is a significant contributor to the depletion of the ozone layer.
• The presence of NO2 in the stratosphere leads to complex chemical reactions that break down ozone (O3) molecules.
• Regulations and technological advancements are continuously being developed to mitigate the impact of NO2 emissions from supersonic aircrafts.

Additional Information

• Stratosphere
  • The stratosphere is the second major layer of Earth's atmosphere, just above the troposphere and below the mesosphere.
  • It extends from about 10 km to 50 km above the Earth's surface.
  • This layer contains the ozone layer, which absorbs and scatters ultraviolet solar radiation.
• Ozone Layer
  • The ozone layer is a region of Earth's stratosphere that contains a high concentration of ozone (O3) molecules.
  • It protects living organisms by blocking most of the sun's harmful ultraviolet (UV) radiation.
  • Depletion of the ozone layer leads to increased UV radiation reaching the Earth's surface, causing health and environmental issues.
• Supersonic Aircraft
  • Supersonic aircraft are designed to fly faster than the speed of sound (Mach 1).
  • Examples include military jets like the F-22 Raptor and the retired Concorde commercial airliner.
  • Supersonic flight poses unique challenges, including high fuel consumption and environmental impacts such as NOx emissions.
• Nitrogen Oxides (NOx)
  • NOx is a generic term for the nitrogen oxides that are most relevant for air pollution, including NO and NO2.
  • They are produced from the reaction of nitrogen and oxygen gases in the air during combustion, especially at high temperatures.
  • NOx emissions contribute to smog and acid rain and have harmful effects on human health and the environment.

The correct answer is Sodium hydrogen carbonate.

Key Points

• Baking soda is chemically known as sodium hydrogen carbonate or sodium bicarbonate (NaHCO₃).
• It is a white crystalline powder that is commonly used as a leavening agent in baking.
• Sodium hydrogen carbonate reacts with acidic components in batter, releasing carbon dioxide gas which helps dough rise.
• It is also used in various household cleaning and deodorizing applications due to its mild abrasive properties and ability to neutralize odors.

Additional Information

• Chemical Properties:
  • When heated, sodium hydrogen carbonate decomposes to form sodium carbonate, water, and carbon dioxide.
  • It is amphoteric, meaning it can react with both acids and bases.
• Uses in Medicine:
  • Sodium bicarbonate is used as an antacid to treat acid indigestion and heartburn.
  • It is also used in some medical procedures to manage metabolic acidosis.
• Environmental Impact:
  • It is considered environmentally safe and biodegradable.
  • It can be used to neutralize acidic spills in the environment.
• Historical Context:
  • Baking soda has been used since ancient times, with the Egyptians using natural deposits of natron (a mineral containing sodium bicarbonate) for cleaning purposes.

The correct answer is produce small amount of hydrochloric acid required for digestion.

Key Points

• Salt, primarily sodium chloride, is essential for the production of hydrochloric acid (HCl) in the stomach.
• Hydrochloric acid is a key component of gastric juice, which aids in the digestion of proteins by activating digestive enzymes.
• The presence of hydrochloric acid helps maintain the stomach’s acidic environment, which is crucial for killing harmful bacteria and pathogens ingested with food.
• Sodium ions from salt are also vital for nerve function, muscle contraction, and maintaining fluid balance in the body.

Additional Information

• Hydrochloric Acid (HCl)
  • A strong acid secreted by parietal cells in the stomach lining.
  • It plays a crucial role in breaking down food particles and activating pepsinogen to pepsin, an enzyme that digests proteins.
• Sodium (Na+)
  • An essential electrolyte that helps regulate blood pressure and volume.
  • Important for muscle and nerve function, including the transmission of nerve impulses.
• Electrolytes
  • Minerals in the body that carry an electric charge and are vital for various bodily functions.
  • Includes sodium, potassium, calcium, bicarbonate, magnesium, chloride, and phosphate.
• Gastric Juice
  • A mixture of hydrochloric acid, potassium chloride, and sodium chloride produced by the stomach lining.
  • Essential for digestion and absorption of nutrients, and protection against pathogens.

The correct answer is Potassium Nitrate.

Key Points

• Saltpetre, also known as Potassium Nitrate (KNO₃), is a chemical compound commonly used in ancient India for making gunpowder and fireworks.
• It is composed of potassium, nitrogen, and oxygen, which makes it an excellent oxidizing agent in pyrotechnics and explosives.
• Potassium Nitrate is naturally found in mineral deposits and can also be synthetically produced through chemical processes.
• Its usage in ancient times extended beyond fireworks, including applications in food preservation, fertilizers, and medicine.
• Historically, Saltpetre played a significant role in the development of military technology, particularly gunpowder in various civilizations.

Additional Information

• Oxidizing Agent: Potassium Nitrate acts as a powerful oxidizer, helping release oxygen during combustion, which is vital for fireworks and explosives.
• Pyrotechnics: It is a key component in the manufacturing of fireworks due to its ability to sustain controlled explosions and create vibrant effects.
• Preservation: In ancient times, Potassium Nitrate was also used to preserve food, particularly meat, due to its antimicrobial properties.
• Fertilizer: Potassium Nitrate is widely used in modern agriculture as a nitrogenous fertilizer to boost plant growth and improve crop yield.
• Chemical Formula: The molecular formula of Potassium Nitrate is KNO₃, indicating one potassium atom, one nitrogen atom, and three oxygen atoms.

The correct answer is Sublimation.

Key Points

• Sublimation is a process where a solid changes directly into a gas without passing through the liquid phase.
• Naphthalene, being a volatile solid, can easily undergo sublimation due to its high vapor pressure at relatively low temperatures.
• This method is particularly effective for purifying substances like naphthalene that can sublime, as impurities do not usually sublime at the same temperature.
• Sublimation allows for the separation and purification of naphthalene by heating it until it turns into vapor and then cooling the vapor to get the purified solid.

Additional Information

• Crystallization: A process of forming solid crystals from a homogeneous solution. Suitable for substances that have impurities with different solubilities.
• Distillation: A method of separating mixtures based on differences in their volatilities in a boiling liquid mixture. Not suitable for solids like naphthalene.
• Steam Distillation: A separation process for temperature-sensitive materials such as natural aromatic compounds. Not applicable to naphthalene.
• Volatile Solids: Substances that easily vaporize at relatively low temperatures. Naphthalene is an example of a volatile solid.
• Vapor Pressure: The pressure exerted by a vapor in equilibrium with its solid or liquid phase. High vapor pressure facilitates sublimation.

The correct answer is Sodium bicarbonate.

Key Points

• Sodium bicarbonate (NaHCO₃), commonly known as baking soda, is a white crystalline compound that is widely used in cooking and baking as a leavening agent.
• When combined with an acid (like vinegar or lemon juice), it releases carbon dioxide gas, causing dough or batter to rise and become light and fluffy.
• It is also used for neutralizing acids, making it a common ingredient in antacids for treating heartburn and indigestion.
• Baking soda has mild abrasive properties, making it effective for cleaning and deodorizing surfaces.
• It is a naturally occurring compound and can also be produced synthetically through the Solvay process.

Additional Information

• Sodium chloride (NaCl): Commonly known as table salt, it is used in food seasoning and preservation. It is not the same as baking soda.
• Sodium hydroxide (NaOH): Also known as caustic soda or lye, it is a strong alkali used in soap making and industrial cleaning, but it is highly corrosive and not safe for consumption.
• Sodium peroxide (Na₂O₂): It is a strong oxidizing agent used in bleaching and as an oxygen source in chemical reactions. It has no role in cooking or baking.
• Leavening agents: Substances like baking soda and baking powder are categorized as leavening agents as they help baked goods rise by producing carbon dioxide gas during cooking.
• pH and Baking Soda: Sodium bicarbonate is alkaline in nature with a pH of around 8-9, which allows it to neutralize acidic substances and act as a gentle cleaning agent.

The correct answer is Boron.

Key Points

• Boron is widely used as a neutron absorber in nuclear reactors to control the rate of the fission reaction.
• It is primarily used in the form of boron carbide (B₄C) or boric acid in control rods and reactor coolant systems.
• Boron absorbs excess neutrons, helping to regulate the chain reaction and prevent the reactor from overheating or going out of control.
• Its high neutron absorption cross-section makes it an effective material for maintaining nuclear reactor stability.
• Boron compounds are also used in emergency shutdown systems to quickly halt the nuclear fission process when needed.

Additional Information

• Control Rods: Control rods are devices made of materials like boron, cadmium, or hafnium that absorb neutrons to regulate the nuclear chain reaction.
• Neutron Moderators: Substances like graphite and heavy water are used to slow down neutrons to sustain the chain reaction, but they do not control its intensity directly.
• Chain Reaction: A nuclear chain reaction occurs when neutrons produced during fission cause further fissions, releasing energy in a controlled or uncontrolled manner.
• Neutron Absorption Cross-Section: This refers to the likelihood of a material, such as boron, to absorb neutrons. Boron has a high absorption cross-section, making it ideal for nuclear reactor control.
• Types of Nuclear Reactors: Common reactor types include Pressurized Water Reactors (PWRs) and Boiling Water Reactors (BWRs), both of which use boron-based systems for safety and control.

The correct answer is Mg₃(PO₄)₂.

Key Points

• The compound Mg₃(PO₄)₂ is formed due to the combination of magnesium ions (Mg²⁺) and phosphate ions (PO₄^3-) in a ratio of 3:2 to maintain charge balance.
• Magnesium has a charge of +2, while phosphate has a charge of -3. To neutralize the charges, three magnesium ions combine with two phosphate ions.
• The formula Mg₃(PO₄)₂ represents magnesium phosphate, a common ionic compound.
• Ionic compounds are formed by the electrostatic attraction between positively charged cations and negatively charged anions.
• This compound is often used in fertilizers and various industrial applications due to its phosphate content.

Additional Information

• Magnesium (Mg):
  • Magnesium is an alkaline earth metal with an atomic number of 12.
  • It commonly forms divalent cations (Mg²⁺) in chemical reactions.
  • It is essential for biological processes like enzyme activation and photosynthesis.
• Phosphate (PO₄^3-):
  • Phosphate is a polyatomic ion consisting of one phosphorus atom bonded to four oxygen atoms.
  • It carries a -3 charge and is widely found in biological systems and minerals.
  • Phosphates are critical for energy storage and transfer in cells (e.g., ATP).
• Ionic Compounds:
  • Ionic compounds are formed by the transfer of electrons, leading to cations and anions.
  • They exhibit high melting and boiling points due to strong ionic bonds.
  • Most ionic compounds dissolve in water, producing electrolyte solutions.
• Charge Balance in Ionic Compounds:
  • The ratio of ions in an ionic compound is determined by their charges to ensure overall neutrality.
  • For Mg₃(PO₄)₂, three Mg²⁺ ions neutralize the charge of two PO₄^3- ions.
  • This balance is a fundamental principle in chemical formula writing.

The correct answer is Magnesium.

Key Points

• Chlorophyll is a coordination compound where the central metal ion is magnesium (Mg).
• Magnesium is coordinated with nitrogen atoms present in the tetrapyrrole ring structure of chlorophyll, known as a porphyrin ring.
• It plays a crucial role in the photosynthetic process by capturing light energy for the conversion of carbon dioxide and water into glucose and oxygen.
• Magnesium stabilizes the structure of chlorophyll and facilitates energy transfer during photosynthesis.
• Without magnesium, the chlorophyll molecule would not function effectively, leading to impaired photosynthesis in plants.

Additional Information

• Chlorophyll Types:
  • The two most common types of chlorophyll are chlorophyll a and chlorophyll b.
  • Chlorophyll a is the primary pigment for photosynthesis, while chlorophyll b acts as an accessory pigment.
• Porphyrin Ring:
  • The porphyrin ring is a cyclic structure composed of four pyrrole molecules interconnected by methine bridges.
  • This ring structure is responsible for the absorption of light energy during photosynthesis.
• Photosynthesis:
  • It is the process by which plants, algae, and certain bacteria convert light energy into chemical energy stored in glucose.
  • Chlorophyll is critical in absorbing light energy, especially in the red and blue wavelengths of the visible spectrum.
• Role of Magnesium in Plants:
  • Magnesium is essential for chlorophyll synthesis and is a vital component of the enzyme systems involved in photosynthesis.
  • A deficiency in magnesium can lead to chlorosis, a condition where leaves turn yellow due to reduced chlorophyll levels.
• Coordination Compounds:
  • These are chemical compounds where a central metal atom or ion is bonded to surrounding ligands through coordinate covalent bonds.
  • In chlorophyll, the magnesium ion is coordinated with nitrogen atoms in the porphyrin ring.

CONCEPT:

Chemical Names and Their Formulas

• Chemicals are often referred to by their common names, but they also have specific chemical formulas that represent their composition.
• Matching chemical names with their correct formulas is essential for understanding their properties and applications.
• Below are common examples:
  • Washing soda: Na₂CO₃·10H₂O (Sodium carbonate decahydrate)
  • Baking soda: NaHCO₃ (Sodium bicarbonate)
  • Bleaching powder: CaOCl₂ (Calcium oxychloride)
  • Gypsum: CaSO₄·2H₂O (Calcium sulfate dihydrate)

Therefore, the correct answer (a) - (3) , (b) - (2) , (c) - (1) , (d) - (4)