acids bases and salts — BSSC Chemistry

50 Questions • 30 Minutes • Chemistry Mock Test in Hindi and English

Sample Questions from this Test

Question 1:

Which of the following acids is predominantly present in tomatoes and spinach?
A.Acetic acid
B.Citric acid
C.Oxalic acid
D.Lactic acid

• Key Fact
Oxalic acid (C₂H₂O₄) is found in leafy greens like spinach, tomatoes, and beetroot.

• Supporting Detail
It is also used in removing rust stains and as a bleaching agent.

• Related Concept
Other organic acids include citric in lemons and acetic in vinegar.

• Why wrong options are wrong
Acetic is in vinegar, citric in citrus fruits, lactic in milk.

• Exam Trick
Remember 'OT' - Oxalic Tomato.

• Additional Info
Formic acid is found in ant stings and fruits.

Question 2:

The term "acid" is derived from which Latin word meaning 'sour'?
A.Acer
B.Acidus
C.Alumen
D.Alkali

• Key Fact
The word "acid" originates from the Latin word 'acidus', meaning sour.

• Supporting Detail
Acids are generally sour in taste and corrosive in nature.

• Related Concept
They release hydrogen ions (H⁺) in aqueous solutions.

• Why wrong options are wrong
'Alumen' is the root for aluminium, not acid.

• Exam Trick
Acid = Acidus = Sour.

• Additional Info
Bases are bitter in taste, unlike sour acids.

Question 3:

What is the neutral colour of a litmus solution when it is neither acidic nor basic?
A.Red
B.Blue
C.Purple
D.Green

• Key Fact
In distilled water (neutral), litmus has a purple colour.

• Supporting Detail
Litmus is extracted from lichens, a plant of the Thallophyta division.

• Related Concept
It turns red in acidic solutions and blue in basic solutions.

• Why wrong options are wrong
Red and blue are its colours in active acidic/basic media, not neutral.

• Exam Trick
Neutral = Purple (mixing red and blue gives purple).

• Additional Info
Universal indicator turns green in neutral solutions, but litmus is purple.

Question 4:

Which concept defines an acid as an "electron pair acceptor"?
A.Arrhenius Theory
B.Bronsted-Lowry Theory
C.Lewis Theory
D.Dalton's Theory

• Key Fact
Lewis Theory defines an acid as an electron pair acceptor (e.g., BF₃, AlCl₃).

• Supporting Detail
A Lewis base is an electron pair donor (e.g., NH₃).

• Related Concept
Arrhenius focuses on H⁺ / OH⁻ ions in water.

• Why wrong options are wrong
Bronsted-Lowry defines acids as proton (H⁺) donors, not electron acceptors.

• Exam Trick
Trick: 'Lewis' starts with L, focus on 'eL'ectrons.

• Additional Info
Bronsted-Lowry involves proton transfer, resulting in conjugate acids/bases.

Question 5:

Consider the following statements:
1. All alkalis are bases.
2. All bases are alkalis.
3. Alkalis are bases that dissolve in water.
Which of the above statements is/are correct?
A.1 and 2 only
B.2 and 3 only
C.1 and 3 only
D.All of the above

• Key Fact
Alkalis are a specific type of base that completely dissolve in water (e.g., NaOH, KOH).

• Supporting Detail
Because they dissolve, all alkalis are bases.

• Related Concept
However, some bases are insoluble in water (e.g., Cu(OH)₂), meaning not all bases are alkalis.

• Why wrong options are wrong
Statement 2 is entirely incorrect.

• Exam Trick
Formula to remember: Alkalis ⊂ Bases (Alkalis are a subset of bases).

• Additional Info
Examples of insoluble bases: Fe(OH)₃, Cu(OH)₂.

Question 6:

Assertion (A): C₂H₅COOH (propanoic acid) is less acidic than HCOOH (formic acid).
Reason (R): The acidic strength of carboxylic acids decreases with increasing alkyl chain length due to the +I (inductive) effect.
A.Both A and R are true, and R is the correct explanation of A
B.Both A and R are true, but R is NOT the correct explanation of A
C.A is true but R is false
D.A is false but R is true

• Key Fact
Formic acid (HCOOH) is the most acidic among simple carboxylic acids as it has no alkyl group.

• Supporting Detail
Alkyl groups like ethyl (C₂H₅) exert an electron-donating inductive effect (+I effect).

• Related Concept
This effect pushes electrons toward the carboxyl group, making the release of the H⁺ ion less favorable.

• Why wrong options are wrong
Thus, longer chains mean weaker acids.

• Exam Trick
Larger Alkyl group = Stronger +I effect = Weaker Acid.

• Additional Info
This principle applies to all organic acids in determining their strength.

Question 7:

What happens when an acid reacts with a metal?
A.It produces carbon dioxide gas
B.It produces hydrogen gas and a salt
C.It forms water and a salt
D.No reaction occurs

• Key Fact
Active metals react with acids to displace hydrogen, forming a salt and releasing Hydrogen (H₂) gas.

• Supporting Detail
Example: Zn + 2HCl → ZnCl₂ + H₂↑.

• Related Concept
Only active metals (above hydrogen in the reactivity series) can do this.

• Why wrong options are wrong
CO₂ is released when acids react with metal carbonates, not pure metals.

• Exam Trick
Metal + Acid = H₂ pop sound test.

• Additional Info
Bases also react with certain metals (like Zn, Al) to release H₂ gas.

Question 8:

Which of the following is NOT a natural acid-base indicator?
A.Petunia flowers
B.Red cabbage leaves
C.Thyme leaves
D.Turmeric

• Key Fact
Thyme leaves are herbs used for culinary and medicinal purposes, not as pH indicators.

• Supporting Detail
Petunia, Geranium, Hydrangea, and Red Cabbage contain a pigment called Anthocyanin, making them natural indicators.

• Related Concept
Turmeric is also a natural indicator (turns red in base).

• Why wrong options are wrong
The question asks for the odd one out; Thyme lacks indicator pigments.

• Exam Trick
Remember 'TRPHG' - Turmeric, Red cabbage, Petunia, Hydrangea, Geranium as natural indicators.

• Additional Info
Olfactory indicators change odour, while these change colour.

Question 9:

Tooth decay starts when the pH of the mouth falls below:
A.7.0
B.6.5
C.5.5
D.1.5

• Key Fact
Tooth decay begins when the pH of the mouth is lower than 5.5.

• Supporting Detail
Bacteria in the mouth produce acids by degrading sugar and food particles.

• Related Concept
Tooth enamel, made of calcium phosphate, gets corroded in an acidic environment below 5.5.

• Why wrong options are wrong
7.0 is neutral, and 1.5 is the pH of gastric juice in the stomach.

• Exam Trick
Use basic toothpastes (pH ~9) to neutralize this acid and prevent decay.

• Additional Info
Acid rain is defined when rainwater pH is below 5.6.

Question 10:

Match Column A with Column B:
Column-A (Indicators)
i. Phenolphthalein in Acid
ii. Phenolphthalein in Base
iii. Methyl Orange in Acid
iv. Methyl Orange in Base

Column-B (Colours)
a. Pink
b. Colorless
c. Yellow
d. Red
A.i-b, ii-a, iii-d, iv-c
B.i-a, ii-b, iii-c, iv-d
C.i-b, ii-c, iii-d, iv-a
D.i-c, ii-b, iii-a, iv-d

• Key Fact
Phenolphthalein is a synthetic indicator that remains colorless in acidic solutions.

• Supporting Detail
Phenolphthalein turns pink in basic (alkaline) solutions.

• Related Concept
Methyl Orange turns red in acidic solutions.

• Why wrong options are wrong
Methyl Orange turns yellow in basic solutions.

• Exam Trick
Trick: 'MY' (Methyl Yellow in base), 'MR' (Methyl Red in acid).

• Additional Info
Litmus turns red in acid and blue in base.

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