Acids MCQ Quiz - Objective Question with Answer for Acids - Download Free PDF

The correct answer is Magnesium hydroxide.

Key Points

• Magnesium hydroxide is commonly used as an antacid to neutralize stomach acid and relieve indigestion and heartburn.
• It is often referred to as "milk of magnesia" due to its milky appearance.
• Magnesium hydroxide works by neutralizing hydrochloric acid in the stomach, thereby increasing the pH level and reducing acidity.
• It is also used as a laxative to relieve constipation by drawing water into the intestines and promoting bowel movements.

Additional Information

• Antacids:
  • Antacids are substances that neutralize stomach acidity and are used to relieve heartburn, indigestion, or an upset stomach.
  • Common active ingredients include magnesium hydroxide, aluminum hydroxide, calcium carbonate, and sodium bicarbonate.
  • Antacids provide quick relief from symptoms but do not heal the underlying cause of acid-related conditions.
• Mechanism of Action:
  • Antacids work by neutralizing the excess hydrochloric acid in the stomach, which increases the pH level and reduces acidity.
  • This action provides relief from pain and discomfort caused by acid reflux and indigestion.
• Other Uses of Magnesium Hydroxide:
  • Besides being an antacid, magnesium hydroxide is also used as a laxative to treat constipation.
  • It works by drawing water into the intestines, which helps to soften stools and stimulate bowel movements.
• Safety and Side Effects:
  • Common side effects of magnesium hydroxide include diarrhea, cramping, and an imbalance in electrolytes if used excessively.
  • Patients with kidney disease should use magnesium hydroxide with caution due to the risk of magnesium accumulation.

The correct answer is Carboxylic acid.

Key Points

• Soaps are defined as the sodium or potassium salts of fatty acids, which are a subcategory of carboxylic acids.
• Carboxylic acids have the general formula R-COOH, where R is a hydrocarbon chain.
• In the soap-making process called saponification, triglycerides react with sodium hydroxide (NaOH) or potassium hydroxide (KOH) to form glycerol and the sodium or potassium salts of the fatty acids.
• The carboxylate end of the soap molecule is hydrophilic (water-attracting), while the long hydrocarbon chain is hydrophobic (water-repelling), which helps in emulsifying oils and greases in water, allowing them to be washed away.
• Common examples of fatty acids used in soap making include stearic acid, palmitic acid, and oleic acid.

 Additional Information

• Sulphuric acid
  • Sulphuric acid (H₂SO₄) is a strong mineral acid used in various industrial processes such as fertilizer production, petroleum refining, and chemical synthesis.
  • It is not used in soap making due to its strong acidic nature and inability to form salts with fatty acids.
• Nitric acid
  • Nitric acid (HNO₃) is another strong mineral acid used primarily in the production of fertilizers, explosives, and in metal processing.
  • It does not react with fatty acids to form soaps.
• Hydrochloric acid
  • Hydrochloric acid (HCl) is a strong acid used in metal cleaning, food processing, and the production of chlorides.
  • It does not participate in the soap-making process.

The correct answer is 1) HCl.

Key Points

• Hydrochloric acid (HCl) is a strong acid commonly found in the stomach, where it aids in digestion.
• HCl is widely used in various industrial processes, including the production of chlorides, fertilizers, and dyes.
• In laboratories, HCl is used as a reagent for titrations and pH control.
• HCl is a colorless and highly corrosive liquid with a pungent smell.

Additional Information

• Acid: A substance that releases hydrogen ions (H+) when dissolved in water, resulting in a pH less than 7.
• Strong Acid: An acid that completely dissociates in water, releasing all its hydrogen ions.
• pH Scale: A scale used to measure the acidity or basicity of a solution, ranging from 0 (highly acidic) to 14 (highly basic), with 7 being neutral.
• Corrosive Substance: A chemical that can cause damage to living tissue or materials through chemical reactions.
• Laboratory Reagent: A substance used in chemical reactions to detect, measure, or produce other substances.

The correct answer is Tartaric acid.

Key Points

• Tartaric acid is an organic acid that is naturally present in many plants, particularly in grapes, bananas, and tamarinds.
• It is commonly used in combination with baking soda to form baking powder, which acts as a leavening agent in baking.
• When combined with baking soda, tartaric acid reacts to produce carbon dioxide gas, which helps dough and batter rise during the baking process.
• This reaction occurs because tartaric acid is a strong acid that can effectively neutralize the alkaline nature of baking soda.
• Baking powder, which contains tartaric acid, is essential in making fluffy and light baked goods such as cakes, muffins, and bread.

 Additional Information

• Lactic acid
  • Lactic acid is found in sour milk products like yogurt and some cottage cheeses.
  • It is produced by the fermentation of lactose by bacteria.
  • Lactic acid is not typically used in baking powder.
• Vinegar
  • Vinegar is an acidic liquid produced from the fermentation of ethanol by acetic acid bacteria.
  • It is often used in cooking and pickling but not usually in baking powder.
• Sodium chloride
  • Sodium chloride, commonly known as table salt, is used to enhance flavor in foods.
  • It does not have the leavening properties needed for baking powder.

The Correct answer is The sting injects methanoic acid.

Key Points

• Bee stings are painful because they inject methanoic acid (also known as formic acid) into the skin.
• This acid causes a burning sensation and can lead to redness, swelling, and inflammation at the site of the sting.
• The injection of methanoic acid triggers the body's immune response, which includes the release of histamines leading to pain and irritation.
• Methanoic acid is a weak acid, but in the concentrated form as injected by bees, it can cause significant discomfort.
• The severity of the reaction can vary based on individual allergies and the number of stings received.

 Additional Information

• The sting releases carbon dioxide gas
  • This is incorrect because a bee sting does not release carbon dioxide gas; instead, it injects a liquid containing methanoic acid.
• The sting injects a mild sugar solution
  • Bee stings do not involve the injection of a sugar solution; they inject methanoic acid which causes pain and inflammation.
• The sting contains a strong base
  • A bee sting does not contain a strong base; it contains methanoic acid, which is an acid, not a base.

The correct answer is The acid present in tomatoes.

Key Points

• Oxalic acid is a chemical compound that occurs naturally in almost every plant to some degree, including fruit, vegetable and grain plants. 
• Tomato contains more than 10 types of acids such as citric acid, malic acid, ascorbic acid, oxalic acid etc. 
• The oxalic acid content of tomatoes is about 50 mg per 100 g serving. 

Additional Information 

• Some natural sources of acid:

The correct answer is option 4.

Key Points

• The sour taste of vinegar is due to the presence of Acetic Acid (CH₃COOH), which is not listed among the options. Hence option 4 is the correct answer. 

Additional Information

• Tartaric acid: Found in tamarind and grapes. 
• Lactic acid: Found in sour milk and curd.
• Citric acid: Found in citrus fruits like lemons and oranges.

The correct answer is Carboxylic acid.

Key Points

• Soaps are defined as the sodium or potassium salts of fatty acids, which are a subcategory of carboxylic acids.
• Carboxylic acids have the general formula R-COOH, where R is a hydrocarbon chain.
• In the soap-making process called saponification, triglycerides react with sodium hydroxide (NaOH) or potassium hydroxide (KOH) to form glycerol and the sodium or potassium salts of the fatty acids.
• The carboxylate end of the soap molecule is hydrophilic (water-attracting), while the long hydrocarbon chain is hydrophobic (water-repelling), which helps in emulsifying oils and greases in water, allowing them to be washed away.
• Common examples of fatty acids used in soap making include stearic acid, palmitic acid, and oleic acid.

 Additional Information

• Sulphuric acid
  • Sulphuric acid (H₂SO₄) is a strong mineral acid used in various industrial processes such as fertilizer production, petroleum refining, and chemical synthesis.
  • It is not used in soap making due to its strong acidic nature and inability to form salts with fatty acids.
• Nitric acid
  • Nitric acid (HNO₃) is another strong mineral acid used primarily in the production of fertilizers, explosives, and in metal processing.
  • It does not react with fatty acids to form soaps.
• Hydrochloric acid
  • Hydrochloric acid (HCl) is a strong acid used in metal cleaning, food processing, and the production of chlorides.
  • It does not participate in the soap-making process.

The correct answer is Magnesium hydroxide.

Key Points

• Magnesium hydroxide is commonly used as an antacid to neutralize stomach acid and relieve indigestion and heartburn.
• It is often referred to as "milk of magnesia" due to its milky appearance.
• Magnesium hydroxide works by neutralizing hydrochloric acid in the stomach, thereby increasing the pH level and reducing acidity.
• It is also used as a laxative to relieve constipation by drawing water into the intestines and promoting bowel movements.

Additional Information

• Antacids:
  • Antacids are substances that neutralize stomach acidity and are used to relieve heartburn, indigestion, or an upset stomach.
  • Common active ingredients include magnesium hydroxide, aluminum hydroxide, calcium carbonate, and sodium bicarbonate.
  • Antacids provide quick relief from symptoms but do not heal the underlying cause of acid-related conditions.
• Mechanism of Action:
  • Antacids work by neutralizing the excess hydrochloric acid in the stomach, which increases the pH level and reduces acidity.
  • This action provides relief from pain and discomfort caused by acid reflux and indigestion.
• Other Uses of Magnesium Hydroxide:
  • Besides being an antacid, magnesium hydroxide is also used as a laxative to treat constipation.
  • It works by drawing water into the intestines, which helps to soften stools and stimulate bowel movements.
• Safety and Side Effects:
  • Common side effects of magnesium hydroxide include diarrhea, cramping, and an imbalance in electrolytes if used excessively.
  • Patients with kidney disease should use magnesium hydroxide with caution due to the risk of magnesium accumulation.

The correct answer is Phosphorous acid.

Key Points

• Phosphorous acid (H₃PO₃) is a dibasic acid.
• It has two acidic hydrogen atoms that can dissociate in an aqueous solution.
• This characteristic allows it to donate two protons, making it a dibasic acid.
• Phosphorous acid is often used in the preparation of phosphite salts, which are important in agriculture and industry.

Additional Information

• Phosphoric Acid (H₃PO₄)
  • Phosphoric acid is a tribasic acid with three hydrogen atoms available for donation.
  • It is widely used in the food industry, especially in cola beverages.
  • In agriculture, it is used as a fertilizer component.
• Boric Acid (H₃BO₃)
  • Boric acid is a weak monobasic acid.
  • It is commonly used as an antiseptic, insecticide, and flame retardant.
• Arsenic Acid (H₃AsO₄)
  • Arsenic acid is a tribasic acid similar to phosphoric acid.
  • It is used in the manufacture of arsenate wood preservatives.
• Acidity
  • Acidity refers to the ability of a substance to donate hydrogen ions (H⁺) in an aqueous solution.
  • Acids are classified based on the number of hydrogen ions they can donate (monobasic, dibasic, tribasic).

The correct answer is 1) HCl.

Key Points

• Hydrochloric acid (HCl) is a strong acid commonly found in the stomach, where it aids in digestion.
• HCl is widely used in various industrial processes, including the production of chlorides, fertilizers, and dyes.
• In laboratories, HCl is used as a reagent for titrations and pH control.
• HCl is a colorless and highly corrosive liquid with a pungent smell.

Additional Information

• Acid: A substance that releases hydrogen ions (H+) when dissolved in water, resulting in a pH less than 7.
• Strong Acid: An acid that completely dissociates in water, releasing all its hydrogen ions.
• pH Scale: A scale used to measure the acidity or basicity of a solution, ranging from 0 (highly acidic) to 14 (highly basic), with 7 being neutral.
• Corrosive Substance: A chemical that can cause damage to living tissue or materials through chemical reactions.
• Laboratory Reagent: A substance used in chemical reactions to detect, measure, or produce other substances.

The Correct answer is Both a and b.

Key Points

• The separation of H+ ions from HCl molecules indeed cannot occur in the absence of water. Water is necessary to facilitate the dissociation process.
• Hydrogen ions in an aqueous solution are always shown as H+ (aq) or H3O+ (hydronium ion). This is because hydrogen ions cannot exist freely in water; they combine with water molecules to form hydronium ions.
• When an acid like HCl is dissolved in water, it dissociates into H+ (aq) and Cl- (aq), demonstrating the necessity of water for this process.
• The correct representation of hydrogen ions in water as H+ (aq) or H3O+ ensures a more accurate depiction of their behavior in solution.
• Both statements are correct and together they provide a comprehensive understanding of the behavior of acids in water.

 Additional Information

• Hydronium Ion (H3O+)
  • The hydronium ion is formed when a water molecule accepts a hydrogen ion (proton).
  • It plays a key role in the chemistry of acids and bases in aqueous solutions.
  • Hydronium ions are responsible for the acidic properties of solutions.
• Dissociation in Water
  • Dissociation is the process by which molecules split into smaller particles such as ions.
  • This process is crucial in understanding the behavior of acids, bases, and salts in water.
  • Water acts as a solvent and facilitates the dissociation of ionic compounds.

The correct answer is Tartaric acid.

Key Points

• Tartaric acid is an organic acid that is naturally present in many plants, particularly in grapes, bananas, and tamarinds.
• It is commonly used in combination with baking soda to form baking powder, which acts as a leavening agent in baking.
• When combined with baking soda, tartaric acid reacts to produce carbon dioxide gas, which helps dough and batter rise during the baking process.
• This reaction occurs because tartaric acid is a strong acid that can effectively neutralize the alkaline nature of baking soda.
• Baking powder, which contains tartaric acid, is essential in making fluffy and light baked goods such as cakes, muffins, and bread.

 Additional Information

• Lactic acid
  • Lactic acid is found in sour milk products like yogurt and some cottage cheeses.
  • It is produced by the fermentation of lactose by bacteria.
  • Lactic acid is not typically used in baking powder.
• Vinegar
  • Vinegar is an acidic liquid produced from the fermentation of ethanol by acetic acid bacteria.
  • It is often used in cooking and pickling but not usually in baking powder.
• Sodium chloride
  • Sodium chloride, commonly known as table salt, is used to enhance flavor in foods.
  • It does not have the leavening properties needed for baking powder.

The Correct answer is The sting injects methanoic acid.

Key Points

• Bee stings are painful because they inject methanoic acid (also known as formic acid) into the skin.
• This acid causes a burning sensation and can lead to redness, swelling, and inflammation at the site of the sting.
• The injection of methanoic acid triggers the body's immune response, which includes the release of histamines leading to pain and irritation.
• Methanoic acid is a weak acid, but in the concentrated form as injected by bees, it can cause significant discomfort.
• The severity of the reaction can vary based on individual allergies and the number of stings received.

 Additional Information

• The sting releases carbon dioxide gas
  • This is incorrect because a bee sting does not release carbon dioxide gas; instead, it injects a liquid containing methanoic acid.
• The sting injects a mild sugar solution
  • Bee stings do not involve the injection of a sugar solution; they inject methanoic acid which causes pain and inflammation.
• The sting contains a strong base
  • A bee sting does not contain a strong base; it contains methanoic acid, which is an acid, not a base.

The correct answer is The sting injects methanoic acid.

Key Points

• Bee stings cause pain and irritation because they inject methanoic acid (formic acid), which is a toxic substance.
• Methanoic acid triggers a localized inflammatory reaction, leading to redness, swelling, and pain at the sting site.
• The venom also contains proteins that affect skin cells and the immune system, further aggravating the irritation.
• The acidic nature of the venom lowers the pH at the sting site, intensifying the burning sensation.
• Immediate treatment such as neutralizing the acid with a mild base (like baking soda) can help alleviate the discomfort.

Additional Information

• Methanoic Acid (Formic Acid):
  • A simple carboxylic acid with the chemical formula HCOOH.
  • Commonly found in nature, including in ant venom and bee stings.
• Bee Venom:
  • A complex mixture of proteins, peptides, and enzymes.
  • It contains compounds such as melittin, which can cause pain and inflammation.
• Inflammatory Response:
  • The body’s natural reaction to injury or infection, characterized by redness, swelling, and pain.
  • Involves the release of histamines and other chemicals that increase blood flow to the affected area.
• First Aid for Bee Stings:
  • Remove the stinger by scraping it off with a blunt object (e.g., a credit card).
  • Wash the area with soap and water, then apply a cold pack to reduce swelling.
  • Neutralize the acid with a baking soda paste or apply an antihistamine cream for relief.
• Precautionary Measures:
  • Avoid provoking bees or disturbing their hives.
  • Wear protective clothing when in areas with a high bee population.