1. Assertion (A) : Passengers in a boat are not allowed to stand.
Reason (R) : This may raise the centre of gravity of the boat .
Passengers in a boat are not allowed to stand because it may raise the center of gravity of the boat, making it unstable and increasing the risk of capsizing. Both the assertion and the reason are correct, and the reason correctly explains the assertion.
2. Assertion (A) : Bronze is used for making statues.
Reason (R) :Bronze is an alloy of copper and tin.
Assertion (A): Bronze is used for making statues. (True)
Reason (R): Bronze is an alloy of copper and tin. (True)
Bronze is used for making statues mainly because of its durability, resistance to corrosion, and ability to capture fine details, not just because it is an alloy of copper and tin.
While both statements are true, R does not fully explain A.
3. Assertion (A) : Graphite is slippery and used as a lubricant.
Reason (R) : Graphite has free electrons.
Assertion (A): Graphite is slippery and used as a lubricant. (True)
Reason (R): Graphite has free electrons. (True)
Graphite is slippery because of its layered structure, where weak van der Waals forces allow the layers to slide over each other easily.
The presence of free electrons makes graphite a good conductor of electricity, but it is not the primary reason for its lubricating property.
R is true but does not correctly explain A.
4. Assertion (A) : There is no vaccine for AIDS.
Reason (R) : The AIDS virus changes its genetic code.
Assertion (A): There is no vaccine for AIDS. (True)
Reason (R): The AIDS virus (HIV) changes its genetic code. (True)
HIV mutates rapidly, making it difficult to develop a stable and effective vaccine.
This constant change in its genetic material allows the virus to evade the immune system, which is why a reliable vaccine has not yet been developed.
The reason correctly explains the assertion, option (D) is the correct.
5. Assertion (A) : Telephone wires sag more in summer.
Reason (R) : They expand due to summer heat.
Assertion (A): Telephone wires sag more in summer – True
Reason (R): They expand due to summer heat – True
While expansion due to heat is a valid phenomenon, it directly causes an increase in the length of the wire, leading to sagging.
So, R is true, but it does not fully explain why the wires sag. Other factors like gravity and material properties also contribute to sagging.
6. Assertion (A) : An atom is neutral despite the charged particles in it.
Reason (R) : The neutrons do not have any charge.
An atom remains neutral because the number of positively charged protons is equal to the number of negatively charged electrons, balancing out the overall charge.
Neutrons, found in the nucleus, are neutral particles, meaning they do not contribute to the charge balance.
While it is true that neutrons have no charge, their presence is not the reason an atom is neutral.
7. Assertion (A) : Clothes are not washed properly in hot water.
Reason (R) : Hard water contains many minerals.
The assertion (A)
"Clothes are not washed properly in hot water"
is false because hot water generally helps in cleaning clothes better by dissolving detergent more effectively and removing grease or dirt
The reason (R)
"Hard water contains many minerals"
is true, but it does not directly relate to the assertion. Hard water can reduce the effectiveness of soap, but this is independent of whether the water is hot or cold.
8. Assertion (A) : In India, the judiciary is independent of the executive.
Reason (R) : Judiciary favours the government and helps in the implementation of its plants.
In India, the judiciary is independent of the executive, meaning it functions separately from the government and has the power to review executive actions.
This ensures the rule of law and protects citizens' rights.
However, the claim that "Judiciary favors the government and helps in the implementation of its plans" is false because the judiciary's primary role is to interpret laws, ensure justice, and check any misuse of power by the executive or legislature.
9. An atom is neutral despite the charged particles in it.
Reason (R) : The neutrons do not have any charge.
An atom is neutral because it contains an equal number of positively charged protons and negatively charged electrons, which balance each other out.
It is true that neutrons have no charge, their presence does not explain why an atom is neutral. Therefore, R is true but not the correct explanation of A.
10. Assertion (A) : In India, the judiciary is independent of the executive.
Reason (R) : Judiciary favours the government and helps in the implementation of its plants.
Assertion (A) is true: In India, the judiciary is independent of the executive.
This is ensured by the Constitution, which provides for the separation of powers among the legislature, executive, and judiciary.
Reason (R) is false: The judiciary does not favor the government or help in the implementation of its plans.
Instead, it acts as a guardian of the Constitution and ensures that the government functions within legal limits.
11. Assertion (A) : Clothes are not washed properly in hot water.
Reason (R) : Hard water contains many minerals.
Assertion (A) is false: Hot water actually helps in cleaning clothes better, as it dissolves detergents more effectively and removes dirt and stains.
Reason (R) is true: Hard water contains minerals like calcium and magnesium, which can reduce the effectiveness of soap and detergent, making washing less efficient.
A is false and R is true
12. Assertion (A) : A ship rises as it enters the sea from a river.
Reason (R) : The density of sea water is higher as compared to river water.
According to Archimedes' principle, the buoyant force on an object is equal to the weight of the displaced fluid.
Since seawater is denser, the ship displaces less water to stay afloat, causing it to rise.
13. Assertion (A) : Bangladesh imports jute from India.
Reason (R) : Bangladesh has most of the jute mills.
Assertion (A) is false: Bangladesh does not import jute from India; rather, it exports raw jute to India. India, in turn, processes the jute in its mills.
Reason (R) is false: While Bangladesh does have jute mills, India also has a significant number of jute mills, especially in West Bengal.
Both A and R are false.
14. Assertion (A) : Clothes are not washed properly in hot water.
Reason (R) : Hard water contains many minerals.
Clothes are actually washed better in hot water because heat helps dissolve detergent more effectively and removes dirt and grease.
Assertion (A) is false.
Hard water does contain many minerals like calcium and magnesium, which can interfere with soap lathering, making washing less effective.
Reason (R) is true.
15. Assertion (A) : An atom is neutral despite the charged particles in it.
Reason (R) : The neutrons do not have any charge.
An atom remains neutral because it contains an equal number of positively charged protons and negatively charged electrons, which balance each other out.
However, neutrons are neutral (having no charge), and while they contribute to the mass of the atom, they do not affect its overall electrical charge.
16. Assertion (A) : In India, the judiciary is independent of the executive.
Reason (R) : Judiciary favours the government and helps in the implementation of its plants.
Assertion (A) is true: In India, the judiciary is independent of the executive.
This means that courts function independently, without interference from the government, ensuring the rule of law and upholding citizens' rights.
Reason (R) is false: The judiciary does not favor the government or help in the implementation of its plans.
Instead, it acts as a check on the executive and legislative branches to prevent misuse of power.
17. Assertion (A) : A ship rises as it enters the sea from a river.
Reason (R) : The density of sea water is higher as compared to river water.
A ship rises in seawater because seawater has a higher density than river water, increasing the buoyant force acting on the ship.
18. Assertion (A) : Shivaji developed the guerilla warfare.
Reason (R) : Shivaji feared the Mughals.
Shivaji did develop guerrilla warfare tactics, but it was not because he feared the Mughals.
Instead, he used guerrilla tactics strategically to fight against the Mughals and other powerful enemies in the challenging terrain of the Western Ghats.
His military strategies were based on speed, surprise attacks, and utilizing the natural landscape to his advantage.
19. Assertion (A) : Beri-beri is a viral infection.
Reason (R) : Vitamin deficiency causes diseases.
Beri-beri is not a viral infection; it is caused by a deficiency of vitamin B1 (thiamine). However, it is true that vitamin deficiencies can lead to various diseases, such as scurvy (vitamin C deficiency) and rickets (vitamin D deficiency).
20. Assertion (A) : We feel colder on mountains than on plains.
Reason (R) : Temperature decreases with altitudes.
As we go higher in altitude (such as on mountains), the temperature decreases due to the lapse rate, which means that for every 1,000 meters of ascent, the temperature drops by approximately 6.5°C.
This is why mountains are colder than plains.
21. Assertion (A) : Leaves of plants are green.
Reason (R) : Plants contain chromoplasts, the green pigment.
Leaves of plants are green because they contain chlorophyll, not chromoplasts. Chlorophyll is the green pigment responsible for photosynthesis.
Chromoplasts, on the other hand, contain pigments like carotenoids and are responsible for red, yellow, and orange colors in fruits and flowers.
22. Assertion (A) : Increase in carbon dioxide would melt polar ice.
Reason (R) : Global temperature would rise.
An increase in carbon dioxide (CO₂) leads to the greenhouse effect, trapping heat in the Earth's atmosphere.
This causes a rise in global temperatures, which in turn leads to the melting of polar ice caps. Thus, the reason (R) correctly explains the assertion (A).
23. Assertion (A) : Shivaji developed the guerilla warfare.
Reason (R) : Shivaji feared the Mughals.
Assertion (A): True - Shivaji developed and mastered guerrilla warfare, known as Ganimi Kava, which involved swift attacks, ambushes, and strategic retreats, making effective use of the rugged terrain of the Western Ghats.
Reason (R): False - Shivaji did not develop guerrilla warfare out of fear of the Mughals. Instead, he used it as a tactical advantage against the numerically superior Mughal and Adil Shahi forces, ensuring the survival and expansion of the Maratha Empire.
24. Assertion (A) : Leaves of plants are green.
Reason (R) : Plants contain chromoplasts, the green pigment.
Assertion (A): True – Leaves of plants are green because they contain chlorophyll, a pigment essential for photosynthesis.
Reason (R): False – The green pigment in plants is chlorophyll, which is found in chloroplasts, not chromoplasts.
Chromoplasts contain pigments like carotenoids (yellow, orange, red) and are responsible for the coloration of fruits, flowers, and some other plant parts, but not the green color of leaves.
25. Assertion (A) : Beri-beri is a viral infection.
Reason (R) : Vitamin deficiency causes diseases.
Assertion (A): False = Beri-beri is not a viral infection; it is a nutritional deficiency disease caused by a lack of Vitamin B1 (Thiamine) in the diet.
Reason (R): True = Vitamin deficiency can cause diseases, such as scurvy (Vitamin C deficiency), rickets (Vitamin D deficiency), and beri-beri (Vitamin B1 deficiency).
26. Assertion (A) : We feel colder on mountains than on plains.
Reason (R) : Temperature decreases with altitudes.
Assertion (A): True - We feel colder on mountains than on plains.
Reason (R): True -Temperature decreases with altitude at an average rate of 6.5°C per 1,000 meters (called the lapse rate). This is why mountainous regions are colder than plains.
27. Assertion (A) : Increase in carbon dioxide would melt polar ice.
Reason (R) : Global temperature would rise.
Assertion (A): True - An increase in carbon dioxide (CO₂) leads to global warming, which can cause the melting of polar ice.
Reason (R): True - Global temperature rises due to the greenhouse effect caused by excess CO₂ in the atmosphere.