Base

PYQ-Based (Q1–10)

Which of the following is a base?
a) HCl
b) NaOH
c) CH₃COOH
d) CO₂
✅ b) NaOH
Explanation: Sodium hydroxide is a strong base that dissociates in water to give OH⁻ ions.
(BPSC Assistant 2017)
A base turns red litmus:
a) Blue
b) Green
c) Yellow
d) Colorless
✅ a) Blue
Explanation: Bases turn red litmus paper blue—classic indicator test.
(BPSC Teacher 2023)
Which of the following is a weak base?
a) NaOH
b) KOH
c) NH₄OH
d) Ca(OH)₂
✅ c) NH₄OH
Explanation: Ammonium hydroxide is a weak base and only partially ionizes in water.
(BPSC 2020)
Which of the following is alkaline in nature?
a) Vinegar
b) Lemon juice
c) Baking soda
d) Carbonic acid
✅ c) Baking soda
Explanation: Baking soda (NaHCO₃) is mildly basic in nature.
(BPSC 64th Prelims)
Which of the following is used to neutralize acid spills in labs?
a) Vinegar
b) Ammonia
c) Sodium hydroxide
d) Baking soda
✅ d) Baking soda
Explanation: Baking soda is a mild base used to neutralize acidic spills safely.
(BPSC CDPO 2021)
Which of the following is not a base?
a) Ca(OH)₂
b) NH₄OH
c) NaCl
d) KOH
✅ c) NaCl
Explanation: Sodium chloride is a neutral salt, not a base.
(BPSC Teacher 2022)
Which base is used in soap preparation?
a) NaCl
b) NaOH
c) CaCO₃
d) CH₃COOH
✅ b) NaOH
Explanation: NaOH is used to saponify fats during soap making.
(BPSC Assistant 2018)
The nature of magnesium hydroxide is:
a) Acidic
b) Basic
c) Neutral
d) Amphoteric
✅ b) Basic
Explanation: Mg(OH)₂ is a base used as an antacid.
(BPSC 63rd)
Which of the following is called slaked lime?
a) CaO
b) Ca(OH)₂
c) NaOH
d) Mg(OH)₂
✅ b) Ca(OH)₂
Explanation: Slaked lime is calcium hydroxide.
(BPSC 2015)
Which among the following shows basic character?
a) H₂O
b) HCl
c) NH₃
d) CO₂
✅ c) NH₃
Explanation: Ammonia is a basic gas that forms NH₄OH in water.
(BPSC 65th Prelims)
Which of these is used as an antacid?
a) HCl
b) NaCl
c) Mg(OH)₂
d) CH₃COOH
✅ c) Mg(OH)₂
Explanation: Magnesium hydroxide neutralizes stomach acid and relieves indigestion.
Aqueous solution of base contains:
a) H⁺ ions
b) OH⁻ ions
c) CO₃²⁻ ions
d) Na⁺ ions only
✅ b) OH⁻ ions
Explanation: Bases release hydroxide ions (OH⁻) in water.
Which base is commonly used in drain cleaners?
a) NaOH
b) NH₄OH
c) KOH
d) Ca(OH)₂
✅ a) NaOH
Explanation: Sodium hydroxide is highly caustic and used to clear blocked drains.
The pH value of a strong base is:
a) Less than 3
b) Around 7
c) 7–10
d) More than 11
✅ d) More than 11
Explanation: Strong bases like NaOH have pH closer to 13 or 14.
What is the nature of lime water?
a) Acidic
b) Basic
c) Neutral
d) Amphoteric
✅ b) Basic
Explanation: Lime water is Ca(OH)₂ in water—mildly basic.
A base that is soluble in water is called:
a) Alkali
b) Salt
c) Metal hydroxide
d) Acid
✅ a) Alkali
Explanation: Soluble bases are specifically called alkalis.
Which of the following is an alkali?
a) CaCO₃
b) NaOH
c) SO₂
d) CH₄
✅ b) NaOH
Explanation: NaOH is water-soluble and releases OH⁻ ions.
Which of the following bases is used to make bleaching powder?
a) KOH
b) Ca(OH)₂
c) NaOH
d) Mg(OH)₂
✅ b) Ca(OH)₂
Explanation: Calcium hydroxide reacts with chlorine to make CaOCl₂ (bleaching powder).
Which of the following reacts with base to give salt and water?
a) Metal
b) Acid
c) Carbon dioxide
d) Hydrogen
✅ b) Acid
Explanation: This is a classic neutralization reaction.
Which of the following is an indicator of base?
a) Turmeric
b) Red litmus
c) Methyl orange
d) All of the above
✅ d) All of the above
Explanation: All change color in the presence of a base (turmeric turns red, red litmus turns blue, methyl orange turns yellow).
The common name of NaOH is:
a) Baking soda
b) Caustic soda
c) Washing soda
d) Bleaching powder
✅ b) Caustic soda
Explanation: Caustic soda is the everyday name for sodium hydroxide.
What is the color of phenolphthalein in a basic solution?
a) Colorless
b) Red
c) Pink
d) Blue
✅ c) Pink
Explanation: Phenolphthalein turns pink in basic solutions.
Bases are:
a) Sour in taste
b) Bitter in taste
c) Sweet in taste
d) Salty in taste
✅ b) Bitter in taste
Explanation: Bases like baking soda have a bitter taste.
Which of the following is a weak base?
a) NaOH
b) KOH
c) NH₄OH
d) Ca(OH)₂
✅ c) NH₄OH
Explanation: Ammonium hydroxide is partially ionized in water.
Which base is used to make soft soaps?
a) NaOH
b) KOH
c) NH₄OH
d) Mg(OH)₂
✅ b) KOH
Explanation: Potassium hydroxide gives soft soap with high lather.
Which of these is an amphoteric oxide?
a) ZnO
b) MgO
c) Na₂O
d) CaO
✅ a) ZnO
Explanation: Zinc oxide reacts with both acids and bases.
Which of the following is used in manufacture of paper and textiles?
a) NaOH
b) NH₄OH
c) Mg(OH)₂
d) KOH
✅ a) NaOH
Explanation: NaOH helps in pulp processing and degreasing.
Which compound is used in manufacture of glass?
a) CaO
b) NaOH
c) KOH
d) NH₄OH
✅ a) CaO
Explanation: CaO (lime) is a basic oxide used in glass manufacturing.
Which of the following is a strong alkali?
a) NH₄OH
b) NaOH
c) H₂O
d) Ca(OH)₂
✅ b) NaOH
Explanation: NaOH fully dissociates in water.
Which base is found in toothpaste for neutralizing acid?
a) NaOH
b) KOH
c) Mg(OH)₂
d) NH₄OH
✅ c) Mg(OH)₂
Explanation: It’s gentle and neutralizes mouth acidity.
Bases are:
a) Electron donors
b) Proton donors
c) Electron acceptors
d) Proton acceptors
✅ d) Proton acceptors
Explanation: Bases accept protons (H⁺) in acid-base reactions.
Which ion is responsible for basicity?
a) H⁺
b) Cl⁻
c) OH⁻
d) Na⁺
✅ c) OH⁻
Explanation: Hydroxide ions give basic nature.
Which of the following is used as a laboratory base?
a) KOH
b) NaOH
c) NH₄OH
d) All of the above
✅ d) All of the above
Explanation: All are commonly used bases in chemistry labs.
Which base is used in preparation of soda lime?
a) NaOH
b) KOH
c) Ca(OH)₂
d) NH₄OH
✅ c) Ca(OH)₂
Explanation: Soda lime = NaOH + Ca(OH)₂, used in CO₂ absorption.
Which base is used to absorb acidic gases?
a) NH₄OH
b) NaOH
c) CaCO₃
d) HCl
✅ b) NaOH
Explanation: NaOH neutralizes acidic gases like SO₂, CO₂.
Which base is used in textile bleaching?
a) NaOH
b) KOH
c) NH₄OH
d) Ca(OH)₂
✅ a) NaOH
Explanation: Strong base used in cleaning and bleaching.
Which base is used as floor cleaner?
a) NaOH
b) KOH
c) NH₄OH
d) Mg(OH)₂
✅ c) NH₄OH
Explanation: Ammonium hydroxide is common in household floor cleaners.
Which of these is corrosive to skin?
a) NH₄OH
b) NaOH
c) CaCO₃
d) NaCl
✅ b) NaOH
Explanation: It causes chemical burns—must be handled with care.
Which of the following metals forms basic oxide?
a) Sulphur
b) Phosphorus
c) Calcium
d) Chlorine
✅ c) Calcium
Explanation: Calcium is a metal and forms basic oxide CaO.
Which compound is used in alkaline batteries?
a) NH₄OH
b) KOH
c) Ca(OH)₂
d) Mg(OH)₂
✅ b) KOH
Explanation: KOH acts as electrolyte in alkaline cells.
The reaction of an acid and base produces:
a) Salt only
b) Water only
c) Salt and water
d) Gas
✅ c) Salt and water
Explanation: It’s a neutralization reaction.
Which base is used in hair relaxers and perms?
a) KOH
b) NaOH
c) NH₄OH
d) Mg(OH)₂
✅ b) NaOH
Explanation: Sodium hydroxide is used in strong hair care chemicals.
The bitter taste of base is due to:
a) Salt
b) H⁺ ions
c) OH⁻ ions
d) Chloride
✅ c) OH⁻ ions
Explanation: Hydroxide ions are responsible for the bitter taste.
Which base is used in neutralizing acidic soils?
a) NaOH
b) NH₄OH
c) Ca(OH)₂
d) Mg(OH)₂
✅ c) Ca(OH)₂
Explanation: Slaked lime is used to reduce soil acidity.
Bases can conduct electricity because they:
a) Dissolve in oil
b) Form OH⁻ ions in water
c) React with metals
d) None
✅ b) Form OH⁻ ions in water
Explanation: These ions carry charge, allowing conduction.
A base that does not dissolve in water is:
a) Alkali
b) Weak base
c) Insoluble base
d) Organic base
✅ c) Insoluble base
Explanation: Not all bases dissolve—insoluble ones include Cu(OH)₂.
Which base is not an alkali?
a) NaOH
b) KOH
c) Ca(OH)₂
d) Zn(OH)₂
✅ d) Zn(OH)₂
Explanation: Zinc hydroxide is not water-soluble.
Which base is used in petroleum refining?
a) NaOH
b) KOH
c) NH₄OH
d) Mg(OH)₂
✅ a) NaOH
Explanation: It removes sulfur compounds during petroleum purification.
Which base is used in manufacture of biodiesel (transesterification)?
a) KOH
b) NaOH
c) NH₄OH
d) Ca(OH)₂
✅ b) NaOH
Explanation: Sodium hydroxide acts as a catalyst.
Which of the following is a household base?
a) HCl
b) NH₄OH
c) Ca(OH)₂
d) CH₃COOH
✅ b) NH₄OH
Explanation: Found in many cleaning agents and floor cleaners.