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All questions of Acids, Base and Salts for Class 7 Exam
Acid turns blue litmusA: OrangeB: PinkC: greenD: RedCorrect answer is 'D'. Can you explain this answer?
Acid turns blue litmus
A: Orange
B: Pink
C: green
D: Red
|
Jithin Chawla answered |
Acids turn blue litmus red. Litmus paper is used as indicator to check acids and bases.
Which of the following is a natural indicator- a)Turmeric
- b)Methyl orange
- c)Oxalic acid.
- d)Phenolphthalein
Correct answer is option 'A'. Can you explain this answer?
Which of the following is a natural indicator
a)
Turmeric
b)
Methyl orange
c)
Oxalic acid.
d)
Phenolphthalein
|
Sanjana Kumar answered |
Some of the natural indicators are red cabbage juice, onion paste, turmeric, lemon juice etc. Natural indicators are turmric,litmus,china rose etc are some natural indicators. Some Natural Indicators are red Cabbage juice,turmeric,china rose[hibiscus] and litmus.
Antacids contain -- a)Strong acid
- b)Weak base
- c)Strong base
- d)Weak acid
Correct answer is option 'B'. Can you explain this answer?
Antacids contain -
a)
Strong acid
b)
Weak base
c)
Strong base
d)
Weak acid
|
Kaavya Menon answered |
Antacids are weak bases which are given when a patient is suffering from acidity.
What is the final color of lemon juice when tested with China rose indicator?- a)Dark pink (magenta)
- b)Green
- c)No change
- d)Blue
Correct answer is option 'A'. Can you explain this answer?
a)
Dark pink (magenta)
b)
Green
c)
No change
d)
Blue
|
Rainbow Rise Classes answered |
Lemon juice is acidic, so when tested with China rose indicator, it will turn dark pink (magenta). This color change indicates the acidic nature of the solution, as China rose turns acidic solutions to dark pink.
What substance is commonly used to treat excessively acidic soil?- a)Quick lime (calcium oxide)
- b)Vinegar
- c)Baking soda
- d)Compost
Correct answer is option 'A'. Can you explain this answer?
a)
Quick lime (calcium oxide)
b)
Vinegar
c)
Baking soda
d)
Compost
|
Coachify answered |
Excessively acidic soil is treated with bases like quick lime (calcium oxide) or slaked lime (calcium hydroxide). These substances neutralize the acidity of the soil, improving its suitability for plant growth.
State whether the following statement is True or False:China rose indicator turns acidic solutions to dark pink (magenta) and basic solutions to green.- a)True
- b)False
Correct answer is option 'A'. Can you explain this answer?
State whether the following statement is True or False:
China rose indicator turns acidic solutions to dark pink (magenta) and basic solutions to green.
a)
True
b)
False
|
|
Rainbow Rise Classes answered |
- China rose indicator is like a magic potion that helps us know if a liquid is sour or sweet. When China rose meets something sour, like lemon juice, it turns the color to dark pink. But if it meets something sweet, like soda water, it changes to green.
- So, when China rose indicator meets acidic solutions, it turns them dark pink (magenta). When it meets basic solutions, it changes them to green. That's why the statement is True!
On adding phenolphthalein indicator to a colourless solution, no change is observed. The nature of the solution may be- a)acidic or basic
- b)basic
- c)acidic or neutral
- d)basic or neutral
Correct answer is option 'C'. Can you explain this answer?
On adding phenolphthalein indicator to a colourless solution, no change is observed. The nature of the solution may be
a)
acidic or basic
b)
basic
c)
acidic or neutral
d)
basic or neutral
|
Shiksha Academy answered |
Since phenolphthalein turns pink in a basic solution and remains colourless in acidic and neutral solutions, if there's no change observed upon its addition, the solution must be either acidic or neutral.
Which of the following acid is present in Tomato?- a)Oxalic acid
- b)Tartaric acid
- c)Phosphoric acid
- d)Lactic acid
Correct answer is option 'A'. Can you explain this answer?
Which of the following acid is present in Tomato?
a)
Oxalic acid
b)
Tartaric acid
c)
Phosphoric acid
d)
Lactic acid
|
Jambada Krishnamurthy answered |
Actually tomato contains oxalic acid.
tamarind contains tartaric acid
phosphoric is used for fertilizers, detergents and soft drinks
lactic acid is produced when you do exercises i.e the muscle cells and red blood cells produces lactic acid
so we can conclude that oxalic acid is present in tomato
tamarind contains tartaric acid
phosphoric is used for fertilizers, detergents and soft drinks
lactic acid is produced when you do exercises i.e the muscle cells and red blood cells produces lactic acid
so we can conclude that oxalic acid is present in tomato
What new substance is formed as a result of a neutralization reaction between hydrochloric acid and sodium hydroxide?- a)Carbon dioxide
- b)Sodium chloride
- c)Oxygen gas
- d)Hydrogen gas
Correct answer is option 'B'. Can you explain this answer?
What new substance is formed as a result of a neutralization reaction between hydrochloric acid and sodium hydroxide?
a)
Carbon dioxide
b)
Sodium chloride
c)
Oxygen gas
d)
Hydrogen gas
|
|
Rainbow Rise Classes answered |
In the neutralization reaction between hydrochloric acid (HCl) and sodium hydroxide (NaOH), the new substance formed is sodium chloride (NaCl), commonly known as table salt. This salt is produced along with water (H2O) as the products of the reaction, highlighting the typical outcome of a neutralization process between an acid and a base.
What happens if you put a drop of soap solution on turmeric paper?- a)The paper turns blue
- b)The paper remains yellow
- c)The paper turns red
- d)The paper turns green
Correct answer is option 'C'. Can you explain this answer?
What happens if you put a drop of soap solution on turmeric paper?
a)
The paper turns blue
b)
The paper remains yellow
c)
The paper turns red
d)
The paper turns green
|
|
Sam Earth answered |
Explanation:
•Putting a drop of soap solution on turmeric paper will make the paper turn into red color.
•That is because due to the process of indication.
•Turmeric turns red when reacted with base and green when reacted with acid.
•Soap solution is a base
Conclusion:
Turmeric paper when reacted with soap solution(base) turns the color of the paper red.
•Putting a drop of soap solution on turmeric paper will make the paper turn into red color.
•That is because due to the process of indication.
•Turmeric turns red when reacted with base and green when reacted with acid.
•Soap solution is a base
Conclusion:
Turmeric paper when reacted with soap solution(base) turns the color of the paper red.
State whether the following statement is True or FalseAcids taste sour and bases taste bitter.- a)True
- b)False
Correct answer is option 'A'. Can you explain this answer?
State whether the following statement is True or False
Acids taste sour and bases taste bitter.
a)
True
b)
False
|
Bespoke Classes answered |
- True! Acids like curd, lemon juice, orange juice, and vinegar taste sour because they contain acids.
- On the other hand, bases like baking soda taste bitter.
- So, acids usually have a sour taste, while bases have a bitter taste.
- When you taste something sour like lemon juice, it might have acids in it.
- And if something tastes bitter like baking soda, it could be a base.
- Remember, sour for acids and bitter for bases!
Acid rain is created when substances like ___________ mix with raindrops in the air.- a)Oxygen, Carbon dioxide
- b)Sulphur dioxide, Nitrogen dioxide
- c)Hydrogen, Sulphur dioxide
- d)Nitrogen dioxide, Hydrogen
Correct answer is option 'B'. Can you explain this answer?
Acid rain is created when substances like ___________ mix with raindrops in the air.
a)
Oxygen, Carbon dioxide
b)
Sulphur dioxide, Nitrogen dioxide
c)
Hydrogen, Sulphur dioxide
d)
Nitrogen dioxide, Hydrogen
|
Raksha Roy answered |
Understanding Acid Rain
Acid rain is a significant environmental issue resulting from human activities and natural processes. It occurs when certain pollutants mix with rainwater, leading to harmful effects on ecosystems, buildings, and human health.
Key Pollutants
The primary substances responsible for acid rain are:
Formation of Acid Rain
When sulphur dioxide and nitrogen dioxide mix with raindrops in the atmosphere, the following reactions occur:
These acids dissolve in the rainwater, resulting in acid rain, which has a lower pH than normal rainwater.
Effects of Acid Rain
Acid rain can lead to various detrimental effects, including:
In summary, option 'B' is correct as sulphur dioxide and nitrogen dioxide are the key substances that contribute to the formation of acid rain, making it a pressing environmental concern.
Acid rain is a significant environmental issue resulting from human activities and natural processes. It occurs when certain pollutants mix with rainwater, leading to harmful effects on ecosystems, buildings, and human health.
Key Pollutants
The primary substances responsible for acid rain are:
- Sulphur Dioxide (SO2): This gas is released from burning fossil fuels, such as coal and oil, and from industrial processes. When it enters the atmosphere, it can combine with oxygen and water vapor to form sulfuric acid.
- Nitrogen Dioxide (NO2): This pollutant comes from vehicle emissions and power plants. It reacts with water vapor in the air to produce nitric acid.
Formation of Acid Rain
When sulphur dioxide and nitrogen dioxide mix with raindrops in the atmosphere, the following reactions occur:
- Formation of Sulfuric Acid: SO2 reacts with oxygen and water to form H2SO4 (sulfuric acid).
- Formation of Nitric Acid: NO2 reacts with water to form HNO3 (nitric acid).
These acids dissolve in the rainwater, resulting in acid rain, which has a lower pH than normal rainwater.
Effects of Acid Rain
Acid rain can lead to various detrimental effects, including:
- Damage to forests and vegetation.
- Acidification of lakes and rivers, harming aquatic life.
- Corrosion of buildings and monuments, especially those made of limestone and marble.
- Negative impacts on soil chemistry, affecting agriculture.
In summary, option 'B' is correct as sulphur dioxide and nitrogen dioxide are the key substances that contribute to the formation of acid rain, making it a pressing environmental concern.
Which acid is commonly found in vinegar?- a)Acetic acid
- b)Citric acid
- c)Lactic acid
- d)Oxalic acid
Correct answer is option 'A'. Can you explain this answer?
Which acid is commonly found in vinegar?
a)
Acetic acid
b)
Citric acid
c)
Lactic acid
d)
Oxalic acid
|
Gunjan Lakhani answered |
Acetic acid is the acid commonly found in vinegar. It is a weak acid that gives vinegar its characteristic sour taste and pungent smell. Acetic acid is also widely used in the food industry for pickling and preserving food items.
What color does litmus paper turn when added to an acidic solution?- a)Green
- b)Red
- c)Blue
- d)Yellow
Correct answer is option 'B'. Can you explain this answer?
What color does litmus paper turn when added to an acidic solution?
a)
Green
b)
Red
c)
Blue
d)
Yellow
|
Subset Academy answered |
Litmus paper turns red when added to an acidic solution. This color change is a result of the acidic nature of the solution, which causes the litmus paper to shift its color to red. It is a simple and effective way to test for acidity using a natural indicator like litmus.
What does phenolphthalein indicate when the solution is basic?- a)It turns dark pink
- b)It turns green
- c)It remains colourless
- d)It turns blue
Correct answer is option 'A'. Can you explain this answer?
What does phenolphthalein indicate when the solution is basic?
a)
It turns dark pink
b)
It turns green
c)
It remains colourless
d)
It turns blue
|
Vp Classes answered |
When phenolphthalein is added to a basic solution, it changes its color to dark pink. This change helps us know if a solution is basic or not. So, when you see the pink color, you can tell that the solution is basic.
What is the role of organic matter in treating basic soil?- a)It neutralizes the acidity of the soil
- b)It releases acids that neutralize the basic nature of the soil
- c)It increases the soil's alkalinity
- d)It improves the soil's drainage
Correct answer is option 'B'. Can you explain this answer?
a)
It neutralizes the acidity of the soil
b)
It releases acids that neutralize the basic nature of the soil
c)
It increases the soil's alkalinity
d)
It improves the soil's drainage
|
|
Rainbow Rise Classes answered |
Organic matter, such as compost, releases acids when decomposed. These acids help to neutralize the basic nature of the soil, making it more suitable for plant growth.
What happens in a neutralization reaction?- a)An acid reacts with another acid to form a base and water.
- b)A base reacts with another base to form an acid and water.
- c)An acid reacts with a base to form salt and water.
- d)An acid reacts with a base to form only salt.
Correct answer is option 'C'. Can you explain this answer?
a)
An acid reacts with another acid to form a base and water.
b)
A base reacts with another base to form an acid and water.
c)
An acid reacts with a base to form salt and water.
d)
An acid reacts with a base to form only salt.
|
|
Vp Classes answered |
In a neutralization reaction, an acid reacts with a base to form salt and water. This process is characterized by the combination of H⁺ ions from the acid and OH⁻ ions from the base to form water (H₂O), and the remaining ions form a salt.
What do we call substances that do not change the color of either red or blue litmus paper?- a)Acids
- b)Bases
- c)Neutral solutions
- d)Indicators
Correct answer is option 'C'. Can you explain this answer?
What do we call substances that do not change the color of either red or blue litmus paper?
a)
Acids
b)
Bases
c)
Neutral solutions
d)
Indicators
|
|
Bespoke Classes answered |
Neutral solutions are substances that do not change the color of either red or blue litmus paper. This means they are neither acidic nor basic.
Why is it important to neutralize factory wastes before disposal into water bodies?- a)To enhance the aesthetic value of the water
- b)To increase the nutrient content of the water
- c)To prevent the killing of aquatic organisms due to acid
- d)To speed up the decomposition of organic matter
Correct answer is option 'C'. Can you explain this answer?
a)
To enhance the aesthetic value of the water
b)
To increase the nutrient content of the water
c)
To prevent the killing of aquatic organisms due to acid
d)
To speed up the decomposition of organic matter
|
Divyansh Majumdar answered |
Importance of Neutralizing Factory Wastes Before Disposal into Water Bodies
Preventing the Killing of Aquatic Organisms
- When factory wastes contain acids or other harmful chemicals, they can have devastating effects on aquatic life.
- The acidic nature of the waste can disrupt the pH balance of the water, making it unsuitable for many aquatic organisms.
- Aquatic organisms may suffer from burns, organ damage, or even death when exposed to acidic waste.
Protecting the Ecosystem
- Aquatic organisms play a crucial role in the ecosystem by maintaining the balance of the food chain.
- If these organisms are killed off due to the acidic factory waste, it can lead to a ripple effect throughout the ecosystem.
- Other species that depend on these organisms for food or habitat may also be affected, causing a domino effect of negative consequences.
Promoting Water Quality
- Neutralizing factory wastes before disposal helps to maintain the quality of water bodies.
- Clean water is essential for human consumption, agriculture, and the overall health of the environment.
- By preventing the introduction of harmful chemicals into water bodies, we can ensure that the water remains safe and usable for various purposes.
In conclusion, neutralizing factory wastes before disposal into water bodies is crucial to prevent the killing of aquatic organisms and protect the ecosystem. It also helps to promote water quality and ensure the sustainability of our natural resources.
Preventing the Killing of Aquatic Organisms
- When factory wastes contain acids or other harmful chemicals, they can have devastating effects on aquatic life.
- The acidic nature of the waste can disrupt the pH balance of the water, making it unsuitable for many aquatic organisms.
- Aquatic organisms may suffer from burns, organ damage, or even death when exposed to acidic waste.
Protecting the Ecosystem
- Aquatic organisms play a crucial role in the ecosystem by maintaining the balance of the food chain.
- If these organisms are killed off due to the acidic factory waste, it can lead to a ripple effect throughout the ecosystem.
- Other species that depend on these organisms for food or habitat may also be affected, causing a domino effect of negative consequences.
Promoting Water Quality
- Neutralizing factory wastes before disposal helps to maintain the quality of water bodies.
- Clean water is essential for human consumption, agriculture, and the overall health of the environment.
- By preventing the introduction of harmful chemicals into water bodies, we can ensure that the water remains safe and usable for various purposes.
In conclusion, neutralizing factory wastes before disposal into water bodies is crucial to prevent the killing of aquatic organisms and protect the ecosystem. It also helps to promote water quality and ensure the sustainability of our natural resources.
Acid present in soured curd is- a)Lactic acid
- b)Acetic acid
- c)Tartaric acid
- d)Oxalic add
Correct answer is option 'A'. Can you explain this answer?
Acid present in soured curd is
a)
Lactic acid
b)
Acetic acid
c)
Tartaric acid
d)
Oxalic add
|
Niharika bajaj answered |
Acid present in soured curd is Lactic acid
Explanation:
- Lactic acid is the acid present in soured curd: When milk is left to ferment, it undergoes a process where bacteria convert the lactose (milk sugar) into lactic acid. This gives the curd its characteristic tangy flavor.
- Role of Lactic Acid: Lactic acid is responsible for the sour taste and also helps in preserving the curd by creating an acidic environment that inhibits the growth of harmful bacteria.
- Health Benefits: Lactic acid produced during the fermentation of curd is also beneficial for gut health as it promotes the growth of beneficial bacteria in the gut.
- Other Acids: While lactic acid is the main acid present in soured curd, other acids such as acetic acid (found in vinegar), tartaric acid (found in grapes), and oxalic acid (found in spinach and rhubarb) may be present in other food items but not in curd.
Therefore, the acid present in soured curd is lactic acid, making it a popular and nutritious dairy product enjoyed by many.
Explanation:
- Lactic acid is the acid present in soured curd: When milk is left to ferment, it undergoes a process where bacteria convert the lactose (milk sugar) into lactic acid. This gives the curd its characteristic tangy flavor.
- Role of Lactic Acid: Lactic acid is responsible for the sour taste and also helps in preserving the curd by creating an acidic environment that inhibits the growth of harmful bacteria.
- Health Benefits: Lactic acid produced during the fermentation of curd is also beneficial for gut health as it promotes the growth of beneficial bacteria in the gut.
- Other Acids: While lactic acid is the main acid present in soured curd, other acids such as acetic acid (found in vinegar), tartaric acid (found in grapes), and oxalic acid (found in spinach and rhubarb) may be present in other food items but not in curd.
Therefore, the acid present in soured curd is lactic acid, making it a popular and nutritious dairy product enjoyed by many.
Which of the following is not a base?
- a)Magnesium hydroxide
- b)Calcium hydroxide
- c)Hydrocholric acid
- d)Sodium hydroxide
Correct answer is option 'C'. Can you explain this answer?
Which of the following is not a base?
a)
Magnesium hydroxide
b)
Calcium hydroxide
c)
Hydrocholric acid
d)
Sodium hydroxide
|
Niti joshi answered |
Calcium Carbonate is not a base because:
- Definition of a base:
Bases are substances that can accept protons (H⁺ ions) or donate hydroxide ions (OH⁻ ions) in a chemical reaction. They have a pH greater than 7.
- Calcium Carbonate:
Calcium carbonate (CaCO₃) is a chemical compound that is commonly found in rocks and shells. It is not a base because it does not ionize in water to produce hydroxide ions (OH⁻). When calcium carbonate reacts with acids, it forms salts and releases carbon dioxide gas, but it does not produce hydroxide ions like typical bases.
- Examples of bases:
1. Magnesium hydroxide (Mg(OH)₂)
2. Calcium hydroxide (Ca(OH)₂)
3. Sodium hydroxide (NaOH)
- Acid-Base reactions:
Bases like magnesium hydroxide, calcium hydroxide, and sodium hydroxide can neutralize acids by accepting protons to form water and a salt. This is a characteristic reaction of bases.
In conclusion, calcium carbonate is not considered a base because it does not fit the definition of a base based on its chemical properties and behavior in reactions with acids.
- Definition of a base:
Bases are substances that can accept protons (H⁺ ions) or donate hydroxide ions (OH⁻ ions) in a chemical reaction. They have a pH greater than 7.
- Calcium Carbonate:
Calcium carbonate (CaCO₃) is a chemical compound that is commonly found in rocks and shells. It is not a base because it does not ionize in water to produce hydroxide ions (OH⁻). When calcium carbonate reacts with acids, it forms salts and releases carbon dioxide gas, but it does not produce hydroxide ions like typical bases.
- Examples of bases:
1. Magnesium hydroxide (Mg(OH)₂)
2. Calcium hydroxide (Ca(OH)₂)
3. Sodium hydroxide (NaOH)
- Acid-Base reactions:
Bases like magnesium hydroxide, calcium hydroxide, and sodium hydroxide can neutralize acids by accepting protons to form water and a salt. This is a characteristic reaction of bases.
In conclusion, calcium carbonate is not considered a base because it does not fit the definition of a base based on its chemical properties and behavior in reactions with acids.
How can you identify a sugar solution, hydrochloric acid, and sodium hydroxide using turmeric indicator?- a)Sugar solution turns turmeric red, hydrochloric acid turns it yellow, sodium hydroxide does not change color.
- b)Sugar solution does not change color, hydrochloric acid turns it yellow, sodium hydroxide turns it red.
- c)Sugar solution turns turmeric red, hydrochloric acid remains unchanged, sodium hydroxide turns it yellow.
- d)Sugar solution turns turmeric yellow, hydrochloric acid turns it red, sodium hydroxide remains unchanged.
Correct answer is option 'B'. Can you explain this answer?
a)
Sugar solution turns turmeric red, hydrochloric acid turns it yellow, sodium hydroxide does not change color.
b)
Sugar solution does not change color, hydrochloric acid turns it yellow, sodium hydroxide turns it red.
c)
Sugar solution turns turmeric red, hydrochloric acid remains unchanged, sodium hydroxide turns it yellow.
d)
Sugar solution turns turmeric yellow, hydrochloric acid turns it red, sodium hydroxide remains unchanged.
|
Tutorpedia Coaching answered |
Using turmeric indicator, a sugar solution will not change color, hydrochloric acid will remain unchanged, and sodium hydroxide will turn the turmeric indicator red due to its basic nature.
What is the pH nature of distilled water?- a)Acidic
- b)Basic
- c)Neutral
- d)Saline
Correct answer is option 'C'. Can you explain this answer?
a)
Acidic
b)
Basic
c)
Neutral
d)
Saline
|
|
Coachify answered |
Distilled water is neutral, with a pH of around 7. It does not change the color of either blue or red litmus paper, which signifies its neutral nature.
What is the role of an antacid such as milk of magnesia in treating indigestion?- a)It increases the acidity in the stomach
- b)It helps to digest food more quickly
- c)It neutralizes the excessive acid in the stomach
- d)It provides a temporary relief without affecting acidity
Correct answer is option 'C'. Can you explain this answer?
a)
It increases the acidity in the stomach
b)
It helps to digest food more quickly
c)
It neutralizes the excessive acid in the stomach
d)
It provides a temporary relief without affecting acidity
|
|
Rainbow Rise Classes answered |
Antacids like milk of magnesia contain basic substances that neutralize the excessive acid in the stomach, providing relief from the discomfort and pain associated with indigestion.
How does an ant bite affect the skin, and what can neutralize this effect?- a)The bite injects a basic liquid, which can be neutralized with vinegar
- b)The bite injects an acidic liquid, which can be neutralized with baking soda or calamine solution
- c)The bite injects a neutral liquid, which does not need treatment
- d)The bite injects a saline solution, which can be neutralized with salt
Correct answer is option 'B'. Can you explain this answer?
a)
The bite injects a basic liquid, which can be neutralized with vinegar
b)
The bite injects an acidic liquid, which can be neutralized with baking soda or calamine solution
c)
The bite injects a neutral liquid, which does not need treatment
d)
The bite injects a saline solution, which can be neutralized with salt
|
Keystone Instructors answered |
An ant bite injects formic acid, which is acidic. This effect can be neutralized by applying moist baking soda (sodium hydrogencarbonate) or calamine solution (zinc carbonate), both of which are basic and counteract the acidity.
Topic in NCERT: Ant bite
Line in NCERT: "When an ant bites, it injects the acidic liquid (formic acid) into the skin. The effect of the acid can be neutralised by rubbing moist baking soda (sodium hydrogencarbonate) or calamine solution, which contains zinc carbonate."
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