Important Compounds and their uses MCQ Quiz - Objective Question with Answer for Important Compounds and their uses - Download Free PDF

The correct answer is Sodium carbonate.

Key Points

• Hard water is softened with the sodium component.
• The lasting hardness of the water is removed with washing soda or sodium carbonate.
• The chemical formula for washing soda is Na₂CO₃.10H₂O.
• In water, it binds calcium and magnesium molecules. Adding sodium carbonate (washing soda) or routing the water via an ion-exchange column can soften the water.
• A procedure known as the lime-soda process is used to remove Ca²⁺ and Mg²⁺ from the water supply in large-scale municipal operations.

Important Points

• The caustic white crystalline solid sodium hydroxide (NaOH) easily absorbs moisture until it dissolves.
• NaHCO₃ is the chemical formula for sodium bicarbonate, also known as baking soda or bicarbonate of soda.
• Salt, often known as sodium chloride, is an ionic compound with the chemical formula NaCl with a 1:1 ratio of sodium and chloride ions.

Key Points

• NaHCO₃ is commonly known as baking soda, a mild base used as an antacid to neutralize stomach acid.
• Antacids containing NaHCO₃ relieve symptoms such as heartburn, indigestion, and acid reflux.
• It reacts with hydrochloric acid (HCl) in the stomach to form salt, water, and carbon dioxide, providing relief from acidity.
• NaHCO₃ is often used in combination with other compounds in over-the-counter antacid products.

Additional Information

• Na₂CO₃ (Sodium Carbonate): Commonly known as washing soda, it is a strong base used in cleaning agents but is not suitable as an antacid due to its high alkalinity, which can irritate the stomach lining.
• Na₂SO₄ (Sodium Sulfate): Also known as Glauber's salt, it is a neutral salt and has no antacid properties. It is used in industries and as a laxative in medical applications.
• MgSO₄ (Magnesium Sulfate): Commonly known as Epsom salt, it is used as a laxative and for muscle relaxation, but it does not have antacid properties.

The correct answer is Aluminum chlorohydrate.

Key Points

• Aluminum chlorohydrate is a widely used ingredient in antiperspirants to control sweating.
• It works by temporarily blocking sweat glands, reducing the amount of sweat released to the skin's surface.
• Aluminum chlorohydrate is considered safe for topical use in the concentrations used in over-the-counter antiperspirants.
• It is effective in managing hyperhidrosis (excessive sweating) and is a common choice in commercial antiperspirant products.
• The compound is approved by regulatory agencies like the FDA for use in personal care products.

Additional Information

• Mechanism of Action: Aluminum chlorohydrate forms a gel-like plug within the sweat gland ducts, preventing sweat from reaching the skin's surface.
• Difference Between Antiperspirants and Deodorants: Antiperspirants reduce sweat, while deodorants mask or neutralize odor caused by bacteria on the skin.
• Hyperhidrosis Treatment: For individuals with excessive sweating, prescription-strength antiperspirants containing aluminum salts may be recommended by healthcare professionals.
• Safety Concerns: While some studies have explored the link between aluminum-based antiperspirants and health risks like breast cancer or Alzheimer's disease, no conclusive evidence has been found to establish such connections.
• Other Common Ingredients in Antiperspirants: Compounds like aluminum zirconium tetrachlorohydrex glycine are also used to achieve similar effects as aluminum chlorohydrate.

The correct answer is Graphite.

Key Points

• Graphite is an allotrope of carbon known for its soft and slippery texture.
• It consists of layers of carbon atoms arranged in a hexagonal lattice, connected by weak van der Waals forces, which allow the layers to slide over each other.
• Graphite is widely used as a lubricant and in pencils due to its ability to leave marks on paper.
• Unlike diamond, which is hard and rigid, graphite has a much lower hardness due to its layered structure.
• Its electrical conductivity is high, making it useful in applications such as electrodes and batteries.

Additional Information

• Diamond:
  • Diamond is another allotrope of carbon, known for its extreme hardness and brilliant optical properties.
  • It has a tetrahedral crystal structure, where each carbon atom is bonded to four other carbon atoms.
  • Diamonds are widely used in jewelry and industrial cutting tools.
• Buckminsterfullerene:
  • Also known as "buckyballs," this allotrope consists of carbon atoms arranged in a spherical shape (C60 molecule).
  • It has unique properties, including high chemical stability and potential applications in nanotechnology.
• Van der Waals Forces:
  • These are weak forces of attraction between molecules or layers, such as those found between layers of graphite.
  • They are responsible for the slippery texture of graphite.
• Applications of Graphite:
  • Used in batteries, lubricants, and as a moderator in nuclear reactors.
  • Its thermal and electrical conductivity make it valuable in high-tech industries.

The correct answer is CaCO3.

Key Points

• Chalk is primarily composed of calcium carbonate (CaCO3), a naturally occurring compound.
• Calcium carbonate is a white, insoluble solid found in sedimentary rocks such as limestone and chalk.
• It is formed mainly by the accumulation of marine organism shells, particularly those of plankton, over millions of years.
• Chalk is widely used in various industries, including construction (as a component of cement), agriculture (to neutralize acidic soil), and in classrooms (as blackboard chalk, although modern chalk is often synthetic).
• The molecular formula CaCO3 represents one calcium atom, one carbon atom, and three oxygen atoms.

Additional Information

• Calcium Carbonate Usage:
  • It is used in the production of lime (CaO) and cement.
  • In the pharmaceutical industry, it acts as a calcium supplement and an antacid.
  • In the food industry, it is used as an additive (E170) for acidity regulation.
• Properties of Calcium Carbonate:
  • It has a molar mass of approximately 100.09 g/mol.
  • It is relatively insoluble in water but reacts with acids, releasing carbon dioxide.
  • Its crystalline forms include calcite and aragonite.
• Formation of Chalk:
  • Chalk is formed from the microscopic remains of planktonic organisms such as coccolithophores.
  • The accumulation of these remains over geological time leads to the formation of chalk beds.
• Other Forms of Calcium Carbonate:
  • Marble is a metamorphic form of calcium carbonate.
  • Limestone is a sedimentary form, widely used in construction.
• Environmental Importance:
  • Calcium carbonate plays a role in carbon cycling by trapping carbon dioxide in rock formations.
  • It is also used to combat ocean acidification by neutralizing excess acidity in seawater.

The correct answer is Preserving pickle.

Key Points

• Sodium hydroxide (NaOH) is known as 'caustic soda' and it is a 'high-base' alkali.
• It is used in the manufacture of pulp and paper cloth, drinking water, soap, and detergent.
• In the field of medicine, sodium hydroxide is used for the treatment, control, prevention, and improvement of diseases.

Hint

• Sodium benzoate is used as a preservative for carbonated drinks, jams and fruit juices, and pickles.

The correct answer is Both of them undergo sublimation.

Important Points

• Both camphor and ammonium chloride are solid at room temperature.
• But they are vaporised (gas phase) when heat is applied.
  • This property is called Sublimation.

Key Points

• Sublimation - Direct conversion of a solid into the vapour state is called sublimation.
• The heat of sublimation - Heat required to change a unit mass of solid directly into vapour, at a given temperature, is called the heat of sublimation at that temperature.

Additional Information

• Camphor:
  • Colourless or white crystalline powder, flammable, waxy with a strong mothball-like odour.
  • Molecular Formula: C₁₀H₁₆O.
  • Organic compound.
• Ammonium chloride:
  • Molecular Formula: NH₄Cl
  • Also, called sal ammoniac (White crystalline salt).
  • Inorganic compounds and highly soluble in water, alcohol, methanol, glycerol, etc.
  • Ammonium Chloride gives an acidic solution by dissolving in water.
  • Inorganic compound.

The correct answer is Ethanol.

Key Points

• Ethanol, anhydrous ethyl alcohol has a chemical formula of C2H5OH or CH3CH2OH.
• It can be produced from sugarcane, maize, wheat, etc which are having high starch content. 
• Ethanol can be mixed with the gasoline to form different blends. 
• As the ethanol molecule contains oxygen, it allows the engine to completely combust the fuel, resulting in fewer emissions and thereby reducing the occurrence of environmental pollution.

Additional Information

The correct answer is Limestone.

Key Points

• Limestone is the main ingredient of cement.
  • Limestone is a sedimentary type of rock naturally found on earth.
  • Limestone rock primarily contains calcium carbonate i.e CaCO3.
  • Quartz, clay minerals, pyrite, siderite and feldspar etc. are other minerals found in limestone.
  • It is known by other names like- chalk, coquina, travertine, tufa, lithographic limestone. oolithic limestone etc.

The main ingredients of cement are as follows-

Additional Information 

Other uses of limestone-

The correct answer is Hydrated Sodium carbonate.

• Washing soda is Hydrated Sodium carbonate.

Key Points

• Washing Soda:
  • Its chemical name is sodium carbonate  (Na₂CO₃·10H₂O).
  • It is used in glass, soap, and paper industries.
  • It is also used in removing the permanent hardness of the water.

Additional Information

• Calcium carbonate:
  • Its formula is CaCO_3.
  • It is used as Lime and in toothpaste.
• Sodium chloride is the chemical name of common salt.
  • Its formula is NaCl.
• Sodium bicarbonate:
  • It is the chemical name of Baking soda.
    Its formula is NaHCO₃
  • It is used in Fire extinguishers, bakeries, reagents.

The correct answer is Graphite.

Key Points

• Graphite has a layered structure composed of stacked sheets of six carbon atoms arranged in a hexagonal crystal structure.
• It is the most stable form of pure carbon under standard conditions. Hence Option 3 is correct.
• It is very soft with low specific gravity and high electrical and thermal conductivity.
• Naturally, high temperature and pressure change carbon into graphite.
• Uses:
  • As neutron moderator in certain nuclear reactors,
  • In pencil lead
  • As Electrodes in batteries,
  • As brake linings for heavy vehicles.
  • Brushes of a DC motor

The correct answer is Cu + Sn.

 Additional Information

• An alloy is a homogenous mixture of two or more metals, or a metal and a non-metal. 
• Cu + Zn alloy called Brass. It is used where low friction and corrosion resistance is required, such as locks, hinges, gears, bearings, hose couplings, valves, etc. 
• Cu + Sn alloy called Bronze, are not good conductors of electricity. whereas copper is used for making electrical circuits.
• Pb + Sn alloy called Solder has a low melting point and is used for welding electrical wires together.
• Al + Cu + Mn + Mg alloy called Duralumin. It is strong, hard, lightweight, an alloy of aluminium. It is used for aircraft construction.
• Al - aluminium, Cu - copper, Mn- manganese, Mg- magnesium, Pb- lead, Zn- zinc, Sn- tin.

The correct answer is Mercury.

• Cinnabar (HgS) is an ore of Mercury.

Key Points

• Cinnabar is a toxic mercury sulfide mineral of mercury with a chemical composition of HgS. 
• The name cinnabar is derived from the Greek name kinnabari.
• Its appearance is bright scarlet to brick-red colour.
• Because of its colour, it was used as jewellery and ornaments for thousands of years in many parts of the world.

Additional Information

• Bauxite is an ore of aluminium.

The correct answer is Option 4, i.e Carbon.

• Carbon can form a large number of chemical compounds, at least 10 million in number.
• It also has the highest sublimation point among all the elements.
• It is the 15th most abundant element on Earth’s Crust.
• Graphite, Diamond, Fullerenes are some of the allotropes of Carbon.

The correct answer is NaHCO3.

Key Points

• The common name of Sodium bicarbonate is Baking soda.
• Sodium bicarbonate is non flammable.
• Baking soda is basic in nature.
• Uses of Sodium bicarbonate are the following:-
  • It acts as an antacid that is used to treat stomach
  • It is used in fire extinguishers due to the formation of soapy foam
  • It acts as a pesticide
  • It neutralizes the effect of acid as a neutralizer
  • In the stomach, Reduces the acidity 

Important Points   

• Baking soda was first manufactured by French chemist Nicolas Leblanc.
• It was first manufactured in 1971.

Additional Information

Some popular chemicals are as below-

•  Bleaching Powder - Calcium Chlorohypochlorite
• Caustic Soda - Sodium Hydroxide
• Washing Soda - Sodium Carbonate
• Table Salt - Sodium Chloride