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CLASS VII SCIENCE
CLASS VII SCIENCE
CHAPTER II: EXPLORING SUBSTANCES: ACIDIC, BASIC, AND NEUTRAL
CHAPTER II: EXPLORING SUBSTANCES: ACIDIC, BASIC, AND NEUTRAL
Direct Type Assertion / Reason Correct / Incorrect HOTS Challenging
DIRECT QUESTIONS
DIRECT QUESTIONS
Which of the following substances contains tartaric acid?
A. Curd
B. Vinegar
C. Tamarind
D. Amla
Answer: C. Tamarind
The nature of a solution that does not change the color of either red or blue litmus paper is:
A. Acidic
B. Basic
C. Neutral
D. Corrosive
Answer: C. Neutral
Which of the following is a natural indicator?
A. Methyl orange
B. Phenolphthalein
C. Turmeric
D. Litmus
Answer: C. Turmeric (Note: D is also natural, but Turmeric is a common kitchen indicator)
Bases are ________ in taste and feel ________ to touch.
A. Sour, rough
B. Sweet, sticky
C. Bitter, soapy
D. Salty, smooth
Answer: C. Bitter, soapy
What is the common name for Sodium Hydroxide?
A. Baking soda
B. Caustic soda
C. Washing soda
D. Lime water
Answer: B. Caustic soda
Which acid is present in the sting of an ant?
A. Acetic acid
B. Formic acid
C. Lactic acid
D. Oxalic acid
Answer: B. Formic acid
The reaction between an acid and a base is known as:
A. Fermentation
B. Neutralization
C. Oxidation
D. Reduction
Answer: B. Neutralization
In a neutralization reaction, the products formed are:
A. Acid and Gas
B. Salt and Water
C. Base and Salt
D. Only Water
Answer: B. Salt and Water
Which of the following turns red litmus blue?
A. Lemon juice
B. Vinegar
C. Baking soda solution
D. Soft drinks
Answer: C. Baking soda solution
Magnesium hydroxide is commonly used as:
A. A cleaning agent
B. An antacid
C. A fertilizer
D. A preservative
Answer: B. An antacid
What color does phenolphthalein give in an acidic solution?
A. Pink
B. Colorless
C. Yellow
D. Blue
Answer: B. Colorless
Which acid is found in citrus fruits like oranges and lemons?
A. Citric acid
B. Oxalic acid
C. Maleic acid
D. Tartaric acid
Answer: A. Citric acid
Curd contains which of the following acids?
A. Acetic acid
B. Lactic acid
C. Formic acid
D. Citric acid
Answer: B. Lactic acid
Litmus is extracted from which of the following?
A. Mushroom
B. Lichens
C. Beetroot
D. Rose petals
Answer: B. Lichens
China rose indicator turns basic solutions to which color?
A. Dark pink
B. Green
C. Blue
D. Colorless
Answer: B. Green
Which of the following is an organic acid?
A. Hydrochloric acid
B. Sulphuric acid
C. Nitric acid
D. Acetic acid
Answer: D. Acetic acid
What is the chemical name of Lime water?
A. Calcium hydroxide
B. Magnesium hydroxide
C. Sodium carbonate
D. Potassium hydroxide
Answer: A. Calcium hydroxide
The stomach produces which acid to help in the digestion of food?
A. Sulphuric acid
B. Nitric acid
C. Hydrochloric acid
D. Acetic acid
Answer: C. Hydrochloric acid
Vinegar contains which chemical?
A. Sodium bicarbonate
B. Citric acid
C. Ethanoic acid (Acetic acid)
D. Formic acid
Answer: C. Ethanoic acid (Acetic acid)
When an acid reacts with a metal, which gas is usually evolved?
A. Oxygen
B. Carbon dioxide
C. Hydrogen
D. Nitrogen
Answer: C. Hydrogen
Which of the following is a synthetic indicator?
A. Turmeric
B. China rose
C. Phenolphthalein
D. Litmus
Answer: C. Phenolphthalein
What is the nature of Soap solution?
A. Acidic
B. Basic
C. Neutral
D. Amphoteric
Answer: B. Basic
Ascorbic acid is also known as:
A. Vitamin A
B. Vitamin B
C. Vitamin C
D. Vitamin D
Answer: C. Vitamin C
Milk of Magnesia contains:
A. Calcium hydroxide
B. Sodium hydroxide
C. Magnesium hydroxide
D. Ammonium hydroxide
Answer: C. Magnesium hydroxide
Acid rain is caused by the presence of which gases in the atmosphere?
A. Oxygen and Nitrogen
B. Carbon dioxide, Sulphur dioxide, and Nitrogen dioxide
C. Argon and Helium
D. Methane and Ethane
Answer: B. Carbon dioxide, Sulphur dioxide, and Nitrogen dioxide
Which indicator turns deep pink (magenta) in acidic solutions?
A. Turmeric
B. China rose
C. Litmus
D. Methyl orange
Answer: B. China rose
Window cleaners usually contain:
A. Magnesium hydroxide
B. Ammonium hydroxide
C. Sodium hydroxide
D. Calcium hydroxide
Answer: B. Ammonium hydroxide
What happens when an acid and base are mixed in equal amounts?
A. The solution becomes more acidic
B. The solution becomes more basic
C. Heat is evolved and salt is formed
D. The solution turns blue
Answer: C. Heat is evolved and salt is formed
Which of the following is used to treat acidic soil?
A. Organic matter
B. Quick lime (Calcium oxide)
C. Hydrochloric acid
D. Vinegar
Answer: B. Quick lime (Calcium oxide)
Amla and citrus fruits are rich in:
A. Oxalic acid
B. Lactic acid
C. Ascorbic acid
D. Acetic acid
Answer: C. Ascorbic acid
Spinach contains which acid?
A. Tartaric acid
B. Oxalic acid
C. Formic acid
D. Citric acid
Answer: B. Oxalic acid
Calamine solution is used to treat ant bites because it contains:
A. Sodium hydroxide
B. Zinc carbonate
C. Calcium oxide
D. Potassium nitrate
Answer: B. Zinc carbonate
Which of the following is NOT a base?
A. NaOH
B. KOH
C. Mg(OH)₂
D. HCl
Answer: D. HCl
Blue litmus paper remains blue in:
A. Acidic solution
B. Basic solution
C. Neutral solution
D. Both B and C
Answer: D. Both B and C
The word 'acid' comes from the Latin word 'ocere' which means:
A. Bitter
B. Sweet
C. Sour
D. Salty
Answer: C. Sour
Which of the following is used in the manufacturing of fertilizers?
A. Vinegar
B. Nitric acid
C. Formic acid
D. Citric acid
Answer: B. Nitric acid
Excessive use of chemical fertilizers makes the soil:
A. Basic
B. Neutral
C. Acidic
D. Fertile
Answer: C. Acidic
If a solution turns phenolphthalein pink, its nature is:
A. Acidic
B. Basic
C. Neutral
D. Highly acidic
Answer: B. Basic
Which substance is used to neutralize basic soil?
A. Slaked lime
B. Quick lime
C. Organic matter (compost)
D. Baking soda
Answer: C. Organic matter (compost)
When a drop of dilute sulphuric acid is added to blue litmus paper, it turns:
A. Green
B. Yellow
C. Red
D. Colorless
Answer: C. Red
The color of turmeric indicator in soap solution is:
A. Yellow
B. Red
C. Blue
D. Pink
Answer: B. Red
The process of neutralization is:
A. Endothermic
B. Exothermic
C. Both
D. None
Answer: B. Exothermic
Which of the following salts is formed when HCl reacts with NaOH?
A. Sodium sulphate
B. Sodium chloride
C. Potassium chloride
D. Calcium chloride
Answer: B. Sodium chloride
A substance that changes color in acidic and basic media is called:
A. Catalyst
B. Indicator
C. Solvent
D. Solute
Answer: B. Indicator
Distilled water is:
A. Acidic
B. Basic
C. Neutral
D. Salty
Answer: C. Neutral
Which acid is used in car batteries?
A. Hydrochloric acid
B. Sulphuric acid
C. Nitric acid
D. Acetic acid
Answer: B. Sulphuric acid
The sting of a wasp is basic. Which substance can be used to treat it?
A. Soap
B. Baking soda
C. Vinegar
D. Lime water
Answer: C. Vinegar
Tooth decay is caused by the presence of:
A. Bases
B. Acids
C. Salts
D. Water
Answer: B. Acids
Which of the following is a mineral acid?
A. Citric acid
B. Lactic acid
C. Sulphuric acid
D. Tartaric acid
Answer: C. Sulphuric acid
Common salt is obtained from:
A. Acid and Metal
B. Sea water
C. Rock salt
D. Both B and C
Answer: D. Both B and C
ASSERTION AND REASON
ASSERTION AND REASON
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.
Assertion (A): Distilled water does not change the color of blue litmus paper.
Reason (R): Distilled water is neutral in nature.
Answer: A. Both A and R are true and R is the correct explanation of A.
Assertion (A): Antacids are used to treat indigestion.
Reason (R): Indigestion is caused by the accumulation of excess base in the stomach.
Answer: C. A is true but R is false.
Assertion (A): Turmeric stain on a white shirt turns red when washed with soap.
Reason (R): Soap solution is basic in nature.
Answer: A. Both A and R are true and R is the correct explanation of A.
Assertion (A): Nitric acid is an organic acid.
Reason (R): Organic acids are naturally occurring acids.
Answer: D. A is false but R is true.
Assertion (A): Neutralization reaction results in the formation of salt and water.
Reason (R): Neutralization is a physical change.
Answer: C. A is true but R is false.
Assertion (A): Factory wastes should be neutralized before discharging into water bodies.
Reason (R): Factory wastes often contain acids that can kill fish and other organisms.
Answer: A. Both A and R are true and R is the correct explanation of A.
Assertion (A): Phenolphthalein is a natural indicator.
Reason (R): Natural indicators are obtained from plants.
Answer: D. A is false but R is true.
Assertion (A): Acid rain can damage historical monuments like the Taj Mahal.
Reason (R): Acid rain reacts with the calcium carbonate of marble.
Answer: A. Both A and R are true and R is the correct explanation of A.
Assertion (A): All substances that taste sour are acidic.
Reason (R): Sour taste is a characteristic property of acids.
Answer: A. Both A and R are true and R is the correct explanation of A.
Assertion (A): Basic soil is treated with organic matter.
Reason (R): Organic matter releases acids that neutralize the basic nature of the soil.
Answer: A. Both A and R are true and R is the correct explanation of A.
CORRECT / INCORRECT STATEMENTS
CORRECT / INCORRECT STATEMENTS
Which of the following statements is INCORRECT?
A. Acids are corrosive in nature.
B. All bases are soluble in water.
C. Acids turn blue litmus red.
D. Salts can be acidic, basic, or neutral.
Answer: B. All bases are soluble in water.
Identify the CORRECT statement:
A. Formic acid is found in apples.
B. Magnesium hydroxide is used as a window cleaner.
C. Neutralization is always accompanied by the evolution of heat.
D. Bases turn blue litmus red.
Answer: C. Neutralization is always accompanied by the evolution of heat.
Which of the following about indicators is CORRECT?
A. Methyl orange turns red in basic solution.
B. Litmus is a synthetic indicator.
C. China rose turns green in basic solution.
D. Phenolphthalein turns pink in acidic solution.
Answer: C. China rose turns green in basic solution.
Find the INCORRECT statement regarding acids:
A. They have a pH less than 7.
B. They react with bases to form salt and water.
C. They turn turmeric indicator red.
D. They are found in many fruits.
Answer: C. They turn turmeric indicator red.
Which statement about Neutralization is INCORRECT?
A. It is a chemical change.
B. A new substance called salt is formed.
C. The resulting solution is always neutral with pH 7.
D. It involves the reaction of H⁺ and OH⁻ ions.
Answer: C. The resulting solution is always neutral with pH 7.
Identify the CORRECT statement about soil treatment:
A. If soil is too acidic, it is treated with organic matter.
B. If soil is too basic, it is treated with quick lime.
C. Quick lime and slaked lime are basic substances.
D. Plants grow best in highly acidic soil.
Answer: C. Quick lime and slaked lime are basic substances.
Select the INCORRECT statement about Vinegar:
A. It contains acetic acid.
B. It is used as a preservative.
C. It turns red litmus blue.
D. It is used in cooking.
Answer: C. It turns red litmus blue.
Which of the following is CORRECT?
A. Lemon juice contains lactic acid.
B. Amla contains ascorbic acid.
C. Grapes contain formic acid.
D. Curd contains citric acid.
Answer: B. Amla contains ascorbic acid.
Identify the INCORRECT statement:
A. Sodium chloride is a neutral salt.
B. Ammonium hydroxide is used in household cleaners.
C. Acids feel soapy to touch.
D. Calamine contains zinc carbonate.
Answer: C. Acids feel soapy to touch.
Which statement is CORRECT?
A. Tartaric acid is found in ant stings.
B. Bases turn turmeric paper red.
C. Litmus paper is a synthetic indicator.
D. Neutralization is an endothermic process.
Answer: B. Bases turn turmeric paper red.
HOTS (HIGHER ORDER THINKING SKILLS)
HOTS (HIGHER ORDER THINKING SKILLS)
A farmer found that the plants in his field were not growing well. On testing, the soil was found to be highly basic. What should the farmer add to the soil?
A. Quick lime
B. Slaked lime
C. Organic matter
D. Common salt
Answer: C. Organic matter
If you have a solution of unknown nature and you add a drop of it to a turmeric paper, and the paper turns red, what can you conclude about the solution?
A. It is acidic.
B. It is neutral.
C. It is basic.
D. It could be either acidic or neutral.
Answer: C. It is basic.
Paheli is suffering from acidity. Her mother gave her a solution of baking soda. Why did this help?
A. Baking soda is an acid and destroys the stomach acid.
B. Baking soda is a base and neutralizes the excess acid.
C. Baking soda reacts to produce more acid to help digestion.
D. Baking soda is neutral and dilutes the acid.
Answer: B. Baking soda is a base and neutralizes the excess acid.
Why are factory wastes treated with basic substances before being discharged into rivers?
A. To make the water more alkaline for fish.
B. To remove the smell of the waste.
C. To neutralize the acids present in the waste.
D. To increase the salt content of the water.
Answer: C. To neutralize the acids present in the waste.
A drop of a liquid was put on blue litmus paper and it stayed blue. A drop of the same liquid was put on red litmus paper and it stayed red. What is the liquid?
A. Lemon juice
B. Soap solution
C. Distilled water
D. Vinegar
Answer: C. Distilled water
Why is a turmeric stain on a white cloth difficult to remove with soap but turns red?
A. Soap is acidic and reacts with turmeric.
B. Soap is basic and reacts with turmeric.
C. Turmeric is a permanent dye.
D. Soap is neutral and changes the color.
Answer: B. Soap is basic and reacts with turmeric.
What will happen if we add an indicator to a solution formed by mixing equal amounts of strong acid and strong base?
A. The indicator will show the color for an acid.
B. The indicator will show the color for a base.
C. The indicator will show its neutral color.
D. The indicator will lose its color.
Answer: C. The indicator will show its neutral color.
Why is it advised to brush teeth after every meal?
A. To make them white.
B. To remove basic food particles.
C. To neutralize the acids produced by bacteria in the mouth.
D. To increase the acid content in the mouth.
Answer: C. To neutralize the acids produced by bacteria in the mouth.
Copper vessels often develop a green layer. To clean them, we use lemon juice or tamarind pulp. Why?
A. The green layer is acidic and the pulp is basic.
B. The green layer is basic and the acid in the pulp neutralizes it.
C. The pulp adds more green color.
D. The pulp is abrasive and scratches the layer.
Answer: B. The green layer is basic and the acid in the pulp neutralizes it.
Which of the following is the most effective way to distinguish between an acid and a base without tasting them?
A. Looking at their color.
B. Using an indicator like litmus or phenolphthalein.
C. Mixing them with water.
D. Touching them.
Answer: B. Using an indicator like litmus or phenolphthalein.
CHALLENGING QUESTIONS
CHALLENGING QUESTIONS
An unknown solution 'X' turns phenolphthalein pink. When solution 'Y' is added to 'X', the pink color disappears. What are the natures of 'X' and 'Y'?
A. X is acidic, Y is basic
B. X is basic, Y is acidic
C. X is neutral, Y is acidic
D. Both are basic
Answer: B. X is basic, Y is acidic
A student has three test tubes containing Hydrochloric acid, Sodium hydroxide, and Sugar solution. He only has Turmeric paper. Which solutions can he identify with certainty?
A. Only Sodium hydroxide
B. Only Hydrochloric acid
C. Sodium hydroxide and Sugar solution
D. All three, if used sequentially
Answer: A. Only Sodium hydroxide (Note: Hydrochloric acid and Sugar solution both leave turmeric yellow)
Why does acid rain have a pH lower than 5.6?
A. Because it contains dissolved Carbon dioxide.
B. Because it contains dissolved Sulphur dioxide and Nitrogen oxides.
C. Because it contains pure water.
D. Because it contains Oxygen.
Answer: B. Because it contains dissolved Sulphur dioxide and Nitrogen oxides.
When baking soda is mixed with lemon juice, bubbles of gas are evolved. If this gas is passed through lime water, the lime water turns milky. The gas is:
A. Hydrogen
B. Oxygen
C. Carbon dioxide
D. Nitrogen
Answer: C. Carbon dioxide
A solution reacts with crushed eggshells to give a gas that turns lime water milky. The solution contains:
A. NaCl
B. HCl
C. LiCl
D. KCl
Answer: B. HCl (Eggshells are made of Calcium Carbonate)
In a neutralization reaction between Sulphuric acid and Potassium hydroxide, what is the salt formed?
A. Potassium sulphate
B. Potassium chloride
C. Sodium sulphate
D. Potassium nitrate
Answer: A. Potassium sulphate
What is the color change of China rose indicator when added to a solution of Magnesium hydroxide?
A. Magenta to Green
B. Colorless to Green
C. Light pink to Green
D. Red to Blue
Answer: C. Light pink to Green
Which of the following is a property of a strong acid?
A. It is found in food items like curd.
B. It completely dissociates into ions in water.
C. It turns red litmus blue.
D. It has a pH of 8.
Answer: B. It completely dissociates into ions in water.
Calamine contains zinc carbonate. If it is applied to an ant sting (formic acid), the reaction produces:
A. Zinc formate, water, and carbon dioxide
B. Zinc oxide and hydrogen
C. Sodium chloride and water
D. Only Zinc formate
Answer: A. Zinc formate, water, and carbon dioxide
A solution of an acid is mixed with a solution of a base in a test tube. The temperature of the mixture:
A. Increases
B. Decreases
C. Remains the same
D. First decreases then increases
Answer: A. Increases (Neutralization is exothermic)
CLASS VII SCIENCE
CLASS VII SCIENCE
CHAPTER II: EXPLORING SUBSTANCES: ACIDIC, BASIC, AND NEUTRAL
CHAPTER II: EXPLORING SUBSTANCES: ACIDIC, BASIC, AND NEUTRAL
Direct Type Assertion / Reason Correct / Incorrect HOTS Challenging
DIRECT QUESTIONS
DIRECT QUESTIONS
Which of the following substances contains tartaric acid?
A. Curd
B. Vinegar
C. Tamarind
D. Amla
Answer: C. Tamarind
The nature of a solution that does not change the color of either red or blue litmus paper is:
A. Acidic
B. Basic
C. Neutral
D. Corrosive
Answer: C. Neutral
Which of the following is a natural indicator?
A. Methyl orange
B. Phenolphthalein
C. Turmeric
D. Litmus
Answer: C. Turmeric (Note: D is also natural, but Turmeric is a common kitchen indicator)
Bases are ________ in taste and feel ________ to touch.
A. Sour, rough
B. Sweet, sticky
C. Bitter, soapy
D. Salty, smooth
Answer: C. Bitter, soapy
What is the common name for Sodium Hydroxide?
A. Baking soda
B. Caustic soda
C. Washing soda
D. Lime water
Answer: B. Caustic soda
Which acid is present in the sting of an ant?
A. Acetic acid
B. Formic acid
C. Lactic acid
D. Oxalic acid
Answer: B. Formic acid
The reaction between an acid and a base is known as:
A. Fermentation
B. Neutralization
C. Oxidation
D. Reduction
Answer: B. Neutralization
In a neutralization reaction, the products formed are:
A. Acid and Gas
B. Salt and Water
C. Base and Salt
D. Only Water
Answer: B. Salt and Water
Which of the following turns red litmus blue?
A. Lemon juice
B. Vinegar
C. Baking soda solution
D. Soft drinks
Answer: C. Baking soda solution
Magnesium hydroxide is commonly used as:
A. A cleaning agent
B. An antacid
C. A fertilizer
D. A preservative
Answer: B. An antacid
What color does phenolphthalein give in an acidic solution?
A. Pink
B. Colorless
C. Yellow
D. Blue
Answer: B. Colorless
Which acid is found in citrus fruits like oranges and lemons?
A. Citric acid
B. Oxalic acid
C. Maleic acid
D. Tartaric acid
Answer: A. Citric acid
Curd contains which of the following acids?
A. Acetic acid
B. Lactic acid
C. Formic acid
D. Citric acid
Answer: B. Lactic acid
Litmus is extracted from which of the following?
A. Mushroom
B. Lichens
C. Beetroot
D. Rose petals
Answer: B. Lichens
China rose indicator turns basic solutions to which color?
A. Dark pink
B. Green
C. Blue
D. Colorless
Answer: B. Green
Which of the following is an organic acid?
A. Hydrochloric acid
B. Sulphuric acid
C. Nitric acid
D. Acetic acid
Answer: D. Acetic acid
What is the chemical name of Lime water?
A. Calcium hydroxide
B. Magnesium hydroxide
C. Sodium carbonate
D. Potassium hydroxide
Answer: A. Calcium hydroxide
The stomach produces which acid to help in the digestion of food?
A. Sulphuric acid
B. Nitric acid
C. Hydrochloric acid
D. Acetic acid
Answer: C. Hydrochloric acid
Vinegar contains which chemical?
A. Sodium bicarbonate
B. Citric acid
C. Ethanoic acid (Acetic acid)
D. Formic acid
Answer: C. Ethanoic acid (Acetic acid)
When an acid reacts with a metal, which gas is usually evolved?
A. Oxygen
B. Carbon dioxide
C. Hydrogen
D. Nitrogen
Answer: C. Hydrogen
Which of the following is a synthetic indicator?
A. Turmeric
B. China rose
C. Phenolphthalein
D. Litmus
Answer: C. Phenolphthalein
What is the nature of Soap solution?
A. Acidic
B. Basic
C. Neutral
D. Amphoteric
Answer: B. Basic
Ascorbic acid is also known as:
A. Vitamin A
B. Vitamin B
C. Vitamin C
D. Vitamin D
Answer: C. Vitamin C
Milk of Magnesia contains:
A. Calcium hydroxide
B. Sodium hydroxide
C. Magnesium hydroxide
D. Ammonium hydroxide
Answer: C. Magnesium hydroxide
Acid rain is caused by the presence of which gases in the atmosphere?
A. Oxygen and Nitrogen
B. Carbon dioxide, Sulphur dioxide, and Nitrogen dioxide
C. Argon and Helium
D. Methane and Ethane
Answer: B. Carbon dioxide, Sulphur dioxide, and Nitrogen dioxide
Which indicator turns deep pink (magenta) in acidic solutions?
A. Turmeric
B. China rose
C. Litmus
D. Methyl orange
Answer: B. China rose
Window cleaners usually contain:
A. Magnesium hydroxide
B. Ammonium hydroxide
C. Sodium hydroxide
D. Calcium hydroxide
Answer: B. Ammonium hydroxide
What happens when an acid and base are mixed in equal amounts?
A. The solution becomes more acidic
B. The solution becomes more basic
C. Heat is evolved and salt is formed
D. The solution turns blue
Answer: C. Heat is evolved and salt is formed
Which of the following is used to treat acidic soil?
A. Organic matter
B. Quick lime (Calcium oxide)
C. Hydrochloric acid
D. Vinegar
Answer: B. Quick lime (Calcium oxide)
Amla and citrus fruits are rich in:
A. Oxalic acid
B. Lactic acid
C. Ascorbic acid
D. Acetic acid
Answer: C. Ascorbic acid
Spinach contains which acid?
A. Tartaric acid
B. Oxalic acid
C. Formic acid
D. Citric acid
Answer: B. Oxalic acid
Calamine solution is used to treat ant bites because it contains:
A. Sodium hydroxide
B. Zinc carbonate
C. Calcium oxide
D. Potassium nitrate
Answer: B. Zinc carbonate
Which of the following is NOT a base?
A. NaOH
B. KOH
C. Mg(OH)₂
D. HCl
Answer: D. HCl
Blue litmus paper remains blue in:
A. Acidic solution
B. Basic solution
C. Neutral solution
D. Both B and C
Answer: D. Both B and C
The word 'acid' comes from the Latin word 'ocere' which means:
A. Bitter
B. Sweet
C. Sour
D. Salty
Answer: C. Sour
Which of the following is used in the manufacturing of fertilizers?
A. Vinegar
B. Nitric acid
C. Formic acid
D. Citric acid
Answer: B. Nitric acid
Excessive use of chemical fertilizers makes the soil:
A. Basic
B. Neutral
C. Acidic
D. Fertile
Answer: C. Acidic
If a solution turns phenolphthalein pink, its nature is:
A. Acidic
B. Basic
C. Neutral
D. Highly acidic
Answer: B. Basic
Which substance is used to neutralize basic soil?
A. Slaked lime
B. Quick lime
C. Organic matter (compost)
D. Baking soda
Answer: C. Organic matter (compost)
When a drop of dilute sulphuric acid is added to blue litmus paper, it turns:
A. Green
B. Yellow
C. Red
D. Colorless
Answer: C. Red
The color of turmeric indicator in soap solution is:
A. Yellow
B. Red
C. Blue
D. Pink
Answer: B. Red
The process of neutralization is:
A. Endothermic
B. Exothermic
C. Both
D. None
Answer: B. Exothermic
Which of the following salts is formed when HCl reacts with NaOH?
A. Sodium sulphate
B. Sodium chloride
C. Potassium chloride
D. Calcium chloride
Answer: B. Sodium chloride
A substance that changes color in acidic and basic media is called:
A. Catalyst
B. Indicator
C. Solvent
D. Solute
Answer: B. Indicator
Distilled water is:
A. Acidic
B. Basic
C. Neutral
D. Salty
Answer: C. Neutral
Which acid is used in car batteries?
A. Hydrochloric acid
B. Sulphuric acid
C. Nitric acid
D. Acetic acid
Answer: B. Sulphuric acid
The sting of a wasp is basic. Which substance can be used to treat it?
A. Soap
B. Baking soda
C. Vinegar
D. Lime water
Answer: C. Vinegar
Tooth decay is caused by the presence of:
A. Bases
B. Acids
C. Salts
D. Water
Answer: B. Acids
Which of the following is a mineral acid?
A. Citric acid
B. Lactic acid
C. Sulphuric acid
D. Tartaric acid
Answer: C. Sulphuric acid
Common salt is obtained from:
A. Acid and Metal
B. Sea water
C. Rock salt
D. Both B and C
Answer: D. Both B and C
ASSERTION AND REASON
ASSERTION AND REASON
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.
Assertion (A): Distilled water does not change the color of blue litmus paper.
Reason (R): Distilled water is neutral in nature.
Answer: A. Both A and R are true and R is the correct explanation of A.
Assertion (A): Antacids are used to treat indigestion.
Reason (R): Indigestion is caused by the accumulation of excess base in the stomach.
Answer: C. A is true but R is false.
Assertion (A): Turmeric stain on a white shirt turns red when washed with soap.
Reason (R): Soap solution is basic in nature.
Answer: A. Both A and R are true and R is the correct explanation of A.
Assertion (A): Nitric acid is an organic acid.
Reason (R): Organic acids are naturally occurring acids.
Answer: D. A is false but R is true.
Assertion (A): Neutralization reaction results in the formation of salt and water.
Reason (R): Neutralization is a physical change.
Answer: C. A is true but R is false.
Assertion (A): Factory wastes should be neutralized before discharging into water bodies.
Reason (R): Factory wastes often contain acids that can kill fish and other organisms.
Answer: A. Both A and R are true and R is the correct explanation of A.
Assertion (A): Phenolphthalein is a natural indicator.
Reason (R): Natural indicators are obtained from plants.
Answer: D. A is false but R is true.
Assertion (A): Acid rain can damage historical monuments like the Taj Mahal.
Reason (R): Acid rain reacts with the calcium carbonate of marble.
Answer: A. Both A and R are true and R is the correct explanation of A.
Assertion (A): All substances that taste sour are acidic.
Reason (R): Sour taste is a characteristic property of acids.
Answer: A. Both A and R are true and R is the correct explanation of A.
Assertion (A): Basic soil is treated with organic matter.
Reason (R): Organic matter releases acids that neutralize the basic nature of the soil.
Answer: A. Both A and R are true and R is the correct explanation of A.
CORRECT / INCORRECT STATEMENTS
CORRECT / INCORRECT STATEMENTS
Which of the following statements is INCORRECT?
A. Acids are corrosive in nature.
B. All bases are soluble in water.
C. Acids turn blue litmus red.
D. Salts can be acidic, basic, or neutral.
Answer: B. All bases are soluble in water.
Identify the CORRECT statement:
A. Formic acid is found in apples.
B. Magnesium hydroxide is used as a window cleaner.
C. Neutralization is always accompanied by the evolution of heat.
D. Bases turn blue litmus red.
Answer: C. Neutralization is always accompanied by the evolution of heat.
Which of the following about indicators is CORRECT?
A. Methyl orange turns red in basic solution.
B. Litmus is a synthetic indicator.
C. China rose turns green in basic solution.
D. Phenolphthalein turns pink in acidic solution.
Answer: C. China rose turns green in basic solution.
Find the INCORRECT statement regarding acids:
A. They have a pH less than 7.
B. They react with bases to form salt and water.
C. They turn turmeric indicator red.
D. They are found in many fruits.
Answer: C. They turn turmeric indicator red.
Which statement about Neutralization is INCORRECT?
A. It is a chemical change.
B. A new substance called salt is formed.
C. The resulting solution is always neutral with pH 7.
D. It involves the reaction of H⁺ and OH⁻ ions.
Answer: C. The resulting solution is always neutral with pH 7.
Identify the CORRECT statement about soil treatment:
A. If soil is too acidic, it is treated with organic matter.
B. If soil is too basic, it is treated with quick lime.
C. Quick lime and slaked lime are basic substances.
D. Plants grow best in highly acidic soil.
Answer: C. Quick lime and slaked lime are basic substances.
Select the INCORRECT statement about Vinegar:
A. It contains acetic acid.
B. It is used as a preservative.
C. It turns red litmus blue.
D. It is used in cooking.
Answer: C. It turns red litmus blue.
Which of the following is CORRECT?
A. Lemon juice contains lactic acid.
B. Amla contains ascorbic acid.
C. Grapes contain formic acid.
D. Curd contains citric acid.
Answer: B. Amla contains ascorbic acid.
Identify the INCORRECT statement:
A. Sodium chloride is a neutral salt.
B. Ammonium hydroxide is used in household cleaners.
C. Acids feel soapy to touch.
D. Calamine contains zinc carbonate.
Answer: C. Acids feel soapy to touch.
Which statement is CORRECT?
A. Tartaric acid is found in ant stings.
B. Bases turn turmeric paper red.
C. Litmus paper is a synthetic indicator.
D. Neutralization is an endothermic process.
Answer: B. Bases turn turmeric paper red.
HOTS (HIGHER ORDER THINKING SKILLS)
HOTS (HIGHER ORDER THINKING SKILLS)
A farmer found that the plants in his field were not growing well. On testing, the soil was found to be highly basic. What should the farmer add to the soil?
A. Quick lime
B. Slaked lime
C. Organic matter
D. Common salt
Answer: C. Organic matter
If you have a solution of unknown nature and you add a drop of it to a turmeric paper, and the paper turns red, what can you conclude about the solution?
A. It is acidic.
B. It is neutral.
C. It is basic.
D. It could be either acidic or neutral.
Answer: C. It is basic.
Paheli is suffering from acidity. Her mother gave her a solution of baking soda. Why did this help?
A. Baking soda is an acid and destroys the stomach acid.
B. Baking soda is a base and neutralizes the excess acid.
C. Baking soda reacts to produce more acid to help digestion.
D. Baking soda is neutral and dilutes the acid.
Answer: B. Baking soda is a base and neutralizes the excess acid.
Why are factory wastes treated with basic substances before being discharged into rivers?
A. To make the water more alkaline for fish.
B. To remove the smell of the waste.
C. To neutralize the acids present in the waste.
D. To increase the salt content of the water.
Answer: C. To neutralize the acids present in the waste.
A drop of a liquid was put on blue litmus paper and it stayed blue. A drop of the same liquid was put on red litmus paper and it stayed red. What is the liquid?
A. Lemon juice
B. Soap solution
C. Distilled water
D. Vinegar
Answer: C. Distilled water
Why is a turmeric stain on a white cloth difficult to remove with soap but turns red?
A. Soap is acidic and reacts with turmeric.
B. Soap is basic and reacts with turmeric.
C. Turmeric is a permanent dye.
D. Soap is neutral and changes the color.
Answer: B. Soap is basic and reacts with turmeric.
What will happen if we add an indicator to a solution formed by mixing equal amounts of strong acid and strong base?
A. The indicator will show the color for an acid.
B. The indicator will show the color for a base.
C. The indicator will show its neutral color.
D. The indicator will lose its color.
Answer: C. The indicator will show its neutral color.
Why is it advised to brush teeth after every meal?
A. To make them white.
B. To remove basic food particles.
C. To neutralize the acids produced by bacteria in the mouth.
D. To increase the acid content in the mouth.
Answer: C. To neutralize the acids produced by bacteria in the mouth.
Copper vessels often develop a green layer. To clean them, we use lemon juice or tamarind pulp. Why?
A. The green layer is acidic and the pulp is basic.
B. The green layer is basic and the acid in the pulp neutralizes it.
C. The pulp adds more green color.
D. The pulp is abrasive and scratches the layer.
Answer: B. The green layer is basic and the acid in the pulp neutralizes it.
Which of the following is the most effective way to distinguish between an acid and a base without tasting them?
A. Looking at their color.
B. Using an indicator like litmus or phenolphthalein.
C. Mixing them with water.
D. Touching them.
Answer: B. Using an indicator like litmus or phenolphthalein.
CHALLENGING QUESTIONS
CHALLENGING QUESTIONS
An unknown solution 'X' turns phenolphthalein pink. When solution 'Y' is added to 'X', the pink color disappears. What are the natures of 'X' and 'Y'?
A. X is acidic, Y is basic
B. X is basic, Y is acidic
C. X is neutral, Y is acidic
D. Both are basic
Answer: B. X is basic, Y is acidic
A student has three test tubes containing Hydrochloric acid, Sodium hydroxide, and Sugar solution. He only has Turmeric paper. Which solutions can he identify with certainty?
A. Only Sodium hydroxide
B. Only Hydrochloric acid
C. Sodium hydroxide and Sugar solution
D. All three, if used sequentially
Answer: A. Only Sodium hydroxide (Note: Hydrochloric acid and Sugar solution both leave turmeric yellow)
Why does acid rain have a pH lower than 5.6?
A. Because it contains dissolved Carbon dioxide.
B. Because it contains dissolved Sulphur dioxide and Nitrogen oxides.
C. Because it contains pure water.
D. Because it contains Oxygen.
Answer: B. Because it contains dissolved Sulphur dioxide and Nitrogen oxides.
When baking soda is mixed with lemon juice, bubbles of gas are evolved. If this gas is passed through lime water, the lime water turns milky. The gas is:
A. Hydrogen
B. Oxygen
C. Carbon dioxide
D. Nitrogen
Answer: C. Carbon dioxide
A solution reacts with crushed eggshells to give a gas that turns lime water milky. The solution contains:
A. NaCl
B. HCl
C. LiCl
D. KCl
Answer: B. HCl (Eggshells are made of Calcium Carbonate)
In a neutralization reaction between Sulphuric acid and Potassium hydroxide, what is the salt formed?
A. Potassium sulphate
B. Potassium chloride
C. Sodium sulphate
D. Potassium nitrate
Answer: A. Potassium sulphate
What is the color change of China rose indicator when added to a solution of Magnesium hydroxide?
A. Magenta to Green
B. Colorless to Green
C. Light pink to Green
D. Red to Blue
Answer: C. Light pink to Green
Which of the following is a property of a strong acid?
A. It is found in food items like curd.
B. It completely dissociates into ions in water.
C. It turns red litmus blue.
D. It has a pH of 8.
Answer: B. It completely dissociates into ions in water.
Calamine contains zinc carbonate. If it is applied to an ant sting (formic acid), the reaction produces:
A. Zinc formate, water, and carbon dioxide
B. Zinc oxide and hydrogen
C. Sodium chloride and water
D. Only Zinc formate
Answer: A. Zinc formate, water, and carbon dioxide
A solution of an acid is mixed with a solution of a base in a test tube. The temperature of the mixture:
A. Increases
B. Decreases
C. Remains the same
D. First decreases then increases
Answer: A. Increases (Neutralization is exothermic)
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