Acids, Bases and Salts MCQ Quiz - Objective Question with Answer for Acids, Bases and Salts - Download Free PDF

The correct answer is Copper.

Key Points

• Copper is one of the least reactive metals with acids, making it less likely to corrode or tarnish when exposed to acidic environments.
• In the reactivity series of metals, copper is placed below hydrogen, indicating its lower reactivity with acids.
• When copper reacts with acids, it does not produce hydrogen gas, unlike more reactive metals such as zinc or iron.
• Due to its low reactivity, copper is often used in plumbing, roofing, and electrical wiring where resistance to corrosion is essential.

Additional Information

• Reactivity Series:
  • The reactivity series is a list of metals arranged in order of decreasing reactivity.
  • Metals higher in the series react more vigorously with acids and other substances.
  • Metals like potassium and sodium are highly reactive, while gold and platinum are the least reactive.
• Hydrogen Production:
  • Reactive metals such as zinc and iron react with acids to produce hydrogen gas.
  • Copper, being less reactive, does not produce hydrogen gas when it reacts with acids.
• Corrosion Resistance:
  • Copper's resistance to corrosion is due to its low reactivity with environmental substances, including acids.
  • This property makes copper suitable for use in various applications where long-term durability is required.
• Uses of Copper:
  • Copper is extensively used in electrical wiring due to its excellent conductivity and resistance to corrosion.
  • It is also used in plumbing, roofing, and industrial machinery.

The Correct answer is Only OH-.

Key Points

• pH is a measure of the hydrogen ion concentration of a solution.
• The pH scale ranges from 0 to 14, with 7 being neutral.
• A pH value greater than 7 indicates a basic solution, while a pH value less than 7 indicates an acidic solution.
• A solution with a pH of 12 is highly basic.
• In a basic solution, the concentration of OH- ions is higher than the concentration of H+ ions.
• Therefore, for a solution with a pH of 12, the concentration of OH- ions is higher.

 Additional Information

• Both H+ and OH- are equal
  • This option would be correct if the pH was exactly 7, as it indicates a neutral solution where H+ and OH- ions are present in equal concentrations.
• More number S2- ions and more Cl-1
  • This option is incorrect because the question specifically asks about the concentration of H+ and OH- ions in relation to pH, not other ions.
• Only H+
  • This option would be correct for an acidic solution where the pH is less than 7.

In a typical acid base neutralization the salt is created by the positive ion from the base and the negative ion from the acid, forming the salt and the hydrogen from the acid combining with the hydroxide from the base to form water.

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 It will turn blue litmus red..

Key Points

• Ammonium chloride (NH₄Cl) is a salt that, when dissolved in water, undergoes hydrolysis to form a weak base (NH₄OH) and a strong acid (HCl).
• The solution of ammonium chloride is acidic in nature due to the presence of the strong acid (HCl).
• When an acidic solution is tested with blue litmus paper, it turns red, indicating the presence of an acid.
• This behavior confirms that the solution of ammonium chloride is acidic and will turn blue litmus paper red.

Additional Information

• Hydrolysis of Salts
  • Hydrolysis refers to the reaction of a salt with water to form an acid and a base.
  • Salts derived from strong acids and weak bases produce acidic solutions.
  • Salts derived from strong bases and weak acids produce basic solutions.
• Litmus Test
  • Litmus paper is a pH indicator used to test whether a solution is acidic or basic.
  • Blue litmus paper turns red under acidic conditions (pH
  • Red litmus paper turns blue under basic conditions (pH > 7).
• Ammonium Chloride
  • Ammonium chloride is a white crystalline salt with the formula NH₄Cl.
  • It is commonly used in fertilizers and as a flavoring agent in some types of licorice.
  • In a laboratory, it is used as a buffer solution and in the preparation of cooling baths.
• pH Scale
  • The pH scale ranges from 0 to 14 and measures the acidity or basicity of a solution.
  • A pH of 7 is considered neutral.
  • pH values less than 7 indicate acidic conditions, while values greater than 7 indicate basic conditions.

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 Sodium hydroxide.

Key Points 

• Sodium hydroxide (NaOH) dissociates completely in water to give Na+ and OH−
• Sodium hydroxide is considered a strong base as all the available [OH] in NaOH is present in the solution as [OH−] and available to accept protons.
• Sodium hydroxide is the strongest base because it totally dissociates to form sodium ions and hydroxide ions.
• These hydroxide ions are treated with hydrogen ions further from the acid and totally ionize the hydrogen ions.
• Producers may utilize sodium hydroxide to manufacture soaps, rayon, paper, products that explode, dyes, and petroleum products.
• Other works that may utilize sodium hydroxide comprise preparing cotton fabric, metal cleaning and preparing, oxide coating, electroplating, and electrolytic extraction.
• It has the pH value of about 14.​

Additional Information

• ​The blood has a normal pH range of 7.35 to 7.45.
• Milk of Magnesia is basic in nature. The pH value of the Milk of Magnesia is 10.5.
• Lemon juice has a pH between 2 and 3.

The correct answer is 10.

Key Points

• Milk of Magnesia is the magnesium compound which acts as an antacid.
• The term milk of magnesia was first used by English pharmacist Charles Henry Phillips in 1872.
• Milk of Magnesia is basic in nature.
• The pH value of the Milk of Magnesia is 10.

Additional Information

• The scale used to express the acidic or alkaline nature of a substance based on the concentration of hydrogen ions in its solution is called a pH scale.
• pH scale was discovered by Soren Sorensen.
  • The pH value of the acids are less than 7 (0 to 7)
• Acid substances usually produce a sour taste.
  • The pH value of the Bases are greater than 7 (7 to 14)
• Base substances usually produce a bitter taste.
• The pH value of the neutral substance is equal to 7.
• The pH value of the pure water is 7.
• The pH value of the blood is close to 7.4.

The correct answer is Red.

Key Points

•  Acid
  • ​Acid changes the colour of blue litmus to Red.
  • A Brnsted-Lowry acid or Lewis acid is a molecule or ion that can either donate a proton (the hydrogen ion, H+) or establish a covalent bond with an electron pair. Proton donors, also known as Brnsted-Lowry acids, are the first class of acids.
  • Proton donors, also referred to as Arrhenius acids, generate the hydronium ion H3O+ under the unique situation of aqueous solutions.
  • The Arrhenius theory was expanded upon by Brnsted and Lowry to take non-aqueous solvents into account.
  • A hydrogen atom is typically bound to a chemical structure in a Brnsted or Arrhenius acid that is still energetically advantageous after the loss of H+.

Additional Information

• Aqueous Arrhenius acids have distinguishing characteristics that serve as a useful definition of an acid. Acids can turn blue litmus red, produce aqueous solutions with a sour taste, and react with bases and some metals (like calcium) to generate salts.
• The Latin word acidus, which means "sour," is where the word acid comes from. While the technical definition solely refers to the solute, an aqueous solution of an acid with a pH lower than 7 is sometimes commonly referred to as "acid" (as in "dissolved in acid"..
• Higher acidity and, thus, a higher concentration of positive hydrogen ions in the solution are indicative of a lower pH. 

The correct answer is Both I and II.

Key Points

• Indicators are the substances that are used to identify whether the given substance is an acid or a base.
• There are two types of indicators:
  • Natural: These indicators are obtained from natural sources like plants. 
  • Turmeric, litmus, china rose petals, etc., are some of the naturally occurring indicators. Hence, option 4 is correct.
  • The most commonly used natural indicator is litmus.
  • It is extracted from lichens.
  • It is available in the form of a solution, or in the form of strips of paper, known as litmus paper.
  • Generally, it is available as red and blue litmus paper.
  • Man-made: Phenolphthalein, Methyl orange are some of the man-made indicators.

Important Points

• The indicators change their color when added to a solution containing an acidic or a basic substance.
• Turmeric is a natural indicator. It contains the substance curcumin which changes color with pH.
• When a substance is basic, the color is red, whereas when the substance is acidic, the color of turmeric turns yellow to brown.
• Films containing aqueous hibiscus extract were developed as a natural pH indicator.
• Natural polymers (chitosan, gelatine, and starch) were used for the film production.
• Great color changes from pink (pH = 2.0) to yellow (pH = 13.0) were observed.
• Acids turn blue litmus red. Bases do not change the color of blue litmus.
• Acids do not change the color of red litmus. Bases turn red litmus blue.

Additional Information 

Some indicators and their color change are given in the table below:

The correct answer is 7.

Key Points

•  A solution's acidity can be determined by looking at its pH, which is a measurement of hydrogen ion concentration. Pure water slightly separates into ions with roughly equal amounts of hydrogen and hydroxyl (OH) ions. [H+] is 107 for a neutral solution, or pH = 7.
• By chance, the amounts of H+ and OH- are equal at pH 7. Because of this, pH 7 is regarded as the neutral pH. The concentration of H+ exceeds the concentration of OH- below pH 7, causing the water to become acidic.
• Because pure water has a pH of exactly 7, a pH value of 7 is considered neutral. Levels under 7 are considered acidic, whereas those over 7 are considered basic or alkaline.​

Additional Information

• pH stands for "Potential of Hydrogen" in its full form.
• The negative logarithm of the concentration of H+ ions is known as pH.
• As a result, the meaning of pH is defined as the strength or power of hydrogen.
• For human life to exist, the serum's pH must be carefully regulated at around 7.4 (a slightly alkaline range of 7.35 to 7.45).

In a typical acid base neutralization the salt is created by the positive ion from the base and the negative ion from the acid, forming the salt and the hydrogen from the acid combining with the hydroxide from the base to form water.

The correct answer is It decreased.

Key Points

• The pH scale measures how acidic or alkaline a substance is.
• A pH scale has a range of 0 to 14. An acidic solution has a pH less than 7 while an alkaline solution has a pH more than 7. The solution with pH 7 is neutral, that is, its neither acidic or basic.
• When the temperature is increased, the degree of decomposition in acidic solution increases, this eventually lowers or decreases the pH of the solution
• Thus, when Babu took some quantity of dilute nitric acid in a test tube and heated the test tube at 70°C for about 10 minutes, the pH of nitric acid decreases with increase in temperature.

The correct answer is Halite.

Key Points

• Halite is the mineral form of sodium chloride (NaCl), commonly known as rock salt.
• Halite forms through the evaporation of seawater and is typically found in sedimentary rock formations.
• It is an evaporite mineral, which means it crystallizes from evaporating brine.
• Commercially, halite is mined for use as table salt, road salt, and in various industrial processes.
• Halite crystals are typically cubic in structure and can range in color from clear to white, and sometimes even shades of pink or blue due to impurities.

 Additional Information

• Hematite
  • Hematite is an iron oxide mineral with the formula Fe₂O₃.
  • It is one of the most abundant minerals on Earth's surface and in the shallow crust.
  • Hematite is primarily used in the production of iron and steel.
  • The mineral can appear in colors such as black to steel or silver-gray, brown to reddish-brown, or red.
• Limonite
  • Limonite is a generic term for a mixture of hydrated iron oxide minerals.
  • It is often used as a low-grade iron ore and can be found in various geological environments.
  • Limonite is typically yellow-brown or ochre-colored.
• Siderite
  • Siderite is a carbonate mineral composed of iron(II) carbonate (FeCO₃).
  • It is a valuable iron mineral, used in the production of iron and steel.
  • Siderite is typically found in sedimentary deposits and can vary in color from yellow to brownish or gray.

The correct answer is 0-7

Explanation:

• The pH scale is a measure of the acidity or basicity of an aqueous solution.
• The scale ranges from 0 to 14, where
  • 7 is neutral,
  • Values less than 7 indicate acidity
  • Values greater than 7 indicate a basic solution.
• Acids are substances that can donate a proton (H+) and have a pH value less than 7.
• The standard pH range for acids is from 0 to 7. This is because acids are characterized by their ability to increase the concentration of hydrogen ions (H+) in a solution, resulting in a lower pH.