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

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 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 CaSO4 · 1/2H2O.

Key Points

• CaSO4 · 1/2H2O is commonly known as Plaster of Paris (POP).
• It is made by heating gypsum (CaSO4 · 2H2O) to about 150°C, which removes water molecules to form CaSO4 · 1/2H2O.
• When mixed with water, Plaster of Paris rehydrates to form a hard mass, which is ideal for setting fractured bones and making casts or molds.
• Doctors use it to create orthopedic casts for immobilizing fractured bones, as it sets quickly and is lightweight.
• Plaster of Paris is also extensively used in construction, artwork, and decorative materials due to its ability to set and form intricate designs.
• This material is non-toxic, making it suitable for medical applications, including fracture treatment and surgical molds.

 Additional Information

• ZnSO4 · 7H2O
  • This compound is known as Zinc Sulfate Heptahydrate.
  • It is used in fertilizers, animal feed supplements, and as a dietary supplement for zinc deficiency.
  • It has no medical application in orthopedic treatments.
• CuSO4 · 5H2O
  • This compound is commonly called Blue Vitriol or Copper Sulfate Pentahydrate.
  • It is used as a fungicide, algaecide, and in electroplating processes.
  • It is not suitable for medical purposes such as setting fractured bones.
• ZnSO4 · 10H2O
  • This is another hydrated form of Zinc Sulfate.
  • Its primary use is in chemical industries, agriculture, and dietary supplements.
  • It does not have any application in orthopedic or medical fields.

The correct answer is Neither I nor II.

Key Points

• Hydrogen chloride:
  • ​Having the chemical formula HCl, the substance hydrogen chloride is a hydrogen halide.
  • HCl is a colourless gas with a strong smell.
  • The aqueous solution of hydrogen chloride is hydrochloric acid.
  • HCl is water soluble.
  • It turns into a colourless liquid at 189 K and a white solid at 159 K when it freezes.
  • Chlorine, aqua regia, and other chlorides are made using HCl.
  • In order to dissolve noble gases, it serves as a solvent.
  • In labs, it serves as a reagent.
• Hydrogen sulphide:
  • Hydrogen sulphide has an offensively awful smell that is comparable to that of rotting eggs.
  • Chalcogen hydride gas having the chemical formula H₂S is known as hydrogen sulfide.
  • It is a dangerous, combustible, and highly corrosive gas.
  • For the purpose of analytical chemistry, it is used to identify cations.
  • The precursor to elemental sulfur is hydrogen sulfide.
  • Hydrogen sulfide is used to synthesize a number of organosulfur compounds, including methanethiol, ethanethiol, and thioglycolic acid.
  • Metallic sulphides, many of which are utilized in the paint industry, are prepared using hydrogen sulfide.
  • The Girdler sulfide technique is used to extract deuterium oxide or heavy water from regular water.​

The correct answer is Sulphuric acid.

Key Points

• In this reaction, Zn metal reacts with dilute H2SO4 to form ZnSO4  and H2 gas is liberated.
• Zn is more reactive than hydrogen and hence it displaces hydrogen from dilute Sulphuric acid.
• The product zinc sulphate and hydrogen gas is entirely different in chemical properties from the reactant.
• Production of hydrogen gas could be seen in the form of bubbles and zinc metal dissolving to form zinc sulphate.
• The reaction is found to be slightly exothermic.

Reaction:

Zn   +  dil.H2SO4  →  ZnSO4  + H2 

Additional Information

• Sulphuric acid is important in mineral processing, oil refining, wastewater processing, and chemical synthesis.
• It has a wide range of applications including in domestic acidic drain cleaners.
• It is also known as oil of vitriol.
• Dilution of concentration Sulphuric acid is highly exothermic process and hence dilution should always be performed by adding the acid to the water and not by adding water to the acid.

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 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

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.