Chemistry

Acids and Bases

594 Questions

Acids and bases questions cover the chemical properties, common examples, and theoretical concepts of acidic and basic substances. Topics include identifying proton acceptors, recognizing amphoteric substances, and knowing the sources of everyday organic acids. These foundational chemistry questions are common across SSC, banking, and railways examinations.

Acid and base propertiesOrganic acidsAmphoteric substancesProton donors and acceptorsChemical formulas

Acids and Bases Questions

Multiple choice chemistry medicinal chemistry antacids and antihistamines therapeutic action of different classes of drugs ph regulation of the stomach

The pair whose both species are used in antacid medicinal preparation is:

  1. $NaHCO _3$ nad $Mg(OH) _2$
  2. $Na _2CO _3$ and $Ca(HCO _3) _2$
  3. $Ca(HCO _3) _2$ and $Mg(OH) _2$
  4. $Ca(OH) _2$ and $NaHCO _3$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
  • An antacid is a substance which neutralizes stomach acidity and is used to relieve heartburn, indigestion or an upset stomach.
  • It is also used to relieve symptoms of extra gas such as belching, bloating, and feelings of pressure/discomfort in the stomach/gut. Aluminum and magnesium antacids work quickly to lower the acid in the stomach.
  • Generally $NaHCO _3$ and $Mg(OH) _2$ are used in antacid medicinal preparation.
Multiple choice chemistry medicinal chemistry antacids and antihistamines therapeutic action of different classes of drugs ph regulation of the stomach

Most commonly used antacids are:

  1. weak bases

  2. strong bases

  3. weak acids

  4. strong acids
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation


Most commonly used antacids are weak bases.
Examples of antacid includes sodium bicarbonate, magnesium hydroxide, magnesium carbonate and aluminium hydroxide. An antacid is the substance which neutralizes the acid and raise the pH to an appropriate level in stomach. They should not be caustic like strong bases.

Multiple choice chemistry medicinal chemistry antacids and antihistamines therapeutic action of different classes of drugs ph regulation of the stomach

What is an antacid?

  1. The substance which neutralizes the acid and raises the pH to an appropriate level in stomach.

  2. The substance which neutralizes the acid and lowers the pH to an appropriate level in stomach.

  3. The substance which neutralizes the base and raises the pH to an appropriate level in stomach.

  4. none of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

An antacid is the substance which neutralizes the acid and raises the pH to an appropriate level in stomach. In other words, antacid is a base which neutralizes excess of acid in the stomach. Examples of antacid include sodium bicarbonate, magnesium hydroxide and aluminium hydroxide. They control the symptoms and not the cause.

Multiple choice chemistry medicinal chemistry antacids and antihistamines therapeutic action of different classes of drugs ph regulation of the stomach

Which of the following substance is an antacid?

  1. $NaCl$
  2. $Mg(OH) _2$
  3. $HCl$
  4. $H _2SO _4$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Due to its mildly basic and non-toxic nature, magnesium hydroxide is widely used as an antacid to neutralize stomach acids and prevent indigestion and heartburn. 

It is also used as a laxative, antiperspirant, underarm deodorant, to treat sores, in wastewater treatment, and as a fire retardant.

Therefore, the correct option is B.

Multiple choice chemistry medicinal chemistry antacids and antihistamines therapeutic action of different classes of drugs ph regulation of the stomach

Examples of antacids are:

  1. sodium hydroxide

  2. sodium bicarbonate

  3. magnesium hydroxide

  4. urea
Reveal answer Fill a bubble to check yourself
B,C Correct answer
Explanation

Antacids: Tension and mental stress escalate the level of acid in bile juice. This hyperacidity can be combated using bases like calcium carbonate, magnesium hydroxide or aluminium hydroxide in the form of tablets or aqueous suspensions. These react with hydrochloric acid in the stomach and neutralize it partially. Gelusil and Digene are two examples of antacids. Antacids must be basic but not enough to make it caustic. Hence, options B and C are appropriate.

Multiple choice chemistry the p-block elements - group 13 study of orthoboric acid some important compounds of boron study of boron

Which of the following is correct statement?

  1. Boric acid is a protonic acid

  2. Beryllium exhibits coordination number of six

  3. Chlorides of both beryllium and aluminium have bridged chloride structures in solid phase
  4. ${B} _{2}{H} _{8}.2{NH} _{3}$ is known as borazone
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Beryllium chloride (BeCl2) and Aluminum chloride (AlCl3) both form polymeric structures with bridged chloride atoms in the solid state.

Multiple choice chemistry the p-block elements - group 13 study of orthoboric acid some important compounds of boron study of boron

$H _{3}BO _{3}$ is a:

  1. monobasic acid and weak Lewis acid

  2. monobasic acid and weak Bronsted acid

  3. monobasic acid and strong Lewis acid

  4. tribasic acid and weak Bronsted acid
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

It is a monobasic acid and a weak lewis acid. It accepts an electron pair from $OH^{-}$.


$B(OH) _{3} + 2H _{2} O \rightleftharpoons [B(OH) _{4} ]^{-} +H _{3} O^{+} $

Option A is correct.

Multiple choice chemistry the p-block elements - group 13 study of orthoboric acid some important compounds of boron study of boron

Boric acid is the trival name for ?

  1. orthoboric acid

  2. metaboric acid

  3. pyroboric acid

  4. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Answer:- (A) Orthoboric acid

Boric acid is a weak, mono-basic Lewis acid of boron, which is often used as an antiseptic, insecticide, flame retardant, neutron absorber, or precursor to other chemical compounds and also known as orthoboric acid (trival name).
The chemical formula of boric acid is $H _3BO _3 \; or \; B{(OH)} _3$.

Multiple choice chemistry the p-block elements - group 13 study of orthoboric acid some important compounds of boron study of boron

Boric acid on heating at $100^oC$ gives:

  1. $B _2O _3$
  2. $H _2B _4O _7$
  3. $HBO _2$
  4. $H _2BO _3$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
  • Orthoboric acid, $H _3BO _3$ is a white crystalline solid, with soapy touch. It is sparingly soluble in water but highly soluble in hot water.
  • On heating, orthoboric acid above 370K forms metaboric acid, $HBO _2$ which on further heating yields boric oxide, $B _2O _3.$
  • Hence option C is correct answer.
Multiple choice chemistry the p-block elements - group 13 study of orthoboric acid some important compounds of boron study of boron

Which of the following is correct statement?

  1. Boric acid is a protonic acid

  2. Beryllium exhibits coordination number of six

  3. Chlorides of both beryllium and aluminium have bridged chloride structures in solid phase
  4. ${B} _{2}{H} _{6}.2{NH} _{3}$ is known as borazone
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

B2H6.2NH3 is known as inorganic benzene or borazine (often referred to as borazone in some contexts).

Multiple choice chemistry the p-block elements - group 13 study of orthoboric acid some important compounds of boron study of boron

Which one of the following is the correct statement?

  1. Boric acid is a protonic avid.
  2. Both ${\text{T}}{{\text{l}}^{{\text{3 + }}}}{\text{and}}\;{\text{A}}{{\text{l}}^{{\text{3 + }}}}$ ions act oxidsing agent in aqueous solution.

  3. Hydrogen bonding in gives it a layered structure

  4. imparts bile colour to the burner flame.
Reveal answer Fill a bubble to check yourself
D Correct answer
Multiple choice chemistry the p-block elements - group 13 study of orthoboric acid some important compounds of boron study of boron

$H _3BO _3$ is :

  1. monobasic and weak Lewis acid.

  2. monobasic and weak Bronsted acid.

  3. monobasic acid and strong Lewis acid.

  4. tribasic acid and weak Bronsted acid.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

$\mathrm{H} _{3}\mathrm{B}\mathrm{O} _{3}(\mathrm{C})$ (orthoboric acid) is a weak lewis acid.

$\mathrm{H} _{3}\mathrm{B}\mathrm{O} _{3}+\mathrm{H} _{2}\mathrm{O} _{-}^{-}\mathrm{E}(\mathrm{O}\mathrm{H}) _{4}^{-}+\mathrm{H}^{\oplus}$

So as it releases one $H^{+}$ so its Monobasic and weak Lewis acid

Hence option A is correct.

Multiple choice chemistry the p-block elements - group 13 study of orthoboric acid some important compounds of boron study of boron

Which of the following statements regarding orthoboric acid $(H _3BO _3)$ is false?

  1. It acts as a weak monobasic acid.

  2. It is soluble in hot water.

  3. It has a planar structure.

  4. It acts as a tribasic acid.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Boric acid, also called hydrogen borate, , is a weak, monobasic lewis acid of boron

Option D only is the wrong statement because it acts as monobasic acid not tri basic .

Hence option D is correct.
Multiple choice chemistry the p-block elements - group 13 study of orthoboric acid some important compounds of boron study of boron

Which one of the following is/are incorrect statement(s)?

  1. The hydroxide of aluminium is more acidic than that of boron.

  2. The hydroxide of boron is basic while that of aluminium is amphoteric.

  3. The hydroxide of boron is acidic while that of aluminium is amphoteric.

  4. The hydroxides of both boron and aluminium are amphoteric.
Reveal answer Fill a bubble to check yourself
A,B,D Correct answer
Explanation

All the elements of this group 13 form oxides and hydroxide.


Boron is the only element in group III of the periodic table which is non-metallic. Metal hydroxides must form a stable cation and anion i.e $OH^-$. Boron does not form a stable cation. This is the reason why metals form basic hydroxides while boron forms a weak acid called boric acid.

 Boron forms acidic oxides and hydroxides, while Al and Ga form amphoteric oxides and hydroxides. In and Tl forms basic oxides and hydroxides.The acidic nature of hydroxides decreases down the group.

Hence options A,B & D are correct.

Multiple choice chemistry the p-block elements - group 13 study of orthoboric acid some important compounds of boron study of boron

Boric acid is a very weak acid but in the presence of certain organic compounds, it acts as a strong acid. Which one of the following organic compound(s) cannot affect such change?

  1. Glycerol

  2. Acetic acid

  3. Ethyl alcohol

  4. Ethylene
Reveal answer Fill a bubble to check yourself
B,C,D Correct answer
Explanation


Option (B),(C),(D) are correct.
Boric acid forms a stable cyclic complex with polyhydroxy compounds like glycerol. This helps in the release of $H^+$ as $H _3O^+$ and therefore boric acid acts as a strong acid. This is not possible with compounds such as acetic acid, ethyl alcohol and ethylene.