Assertion and Reason
Assertion (A) : Passengers in a boat are not allowed to stand. Reason (R) : This may raise the centre of gravity of the boat .
  • A is true but R is false
  • A is false but R is true.
  • Both A and R are false.
  • Both A and R are true and R is the correct explanation of A.
Explanation: 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.
Assertion (A) : Bronze is used for making statues. Reason (R) :Bronze is an alloy of copper and tin.
  • Both A and R are true but R is not the correct explanation of A.
  • Both A and R are true and R is the correct explanation of A.
  • A is true but R is false.
  • A is false but R is true.
Explanation: 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.
Assertion (A) : Graphite is slippery and used as a lubricant. Reason (R) : Graphite has free electrons.
  • Both A and R are true but R is not the correct explanation of A.
  • Both A and R are true and R is the correct explanation of A.
  • A is false but R is true.
  • A is true but R is false.
Explanation: 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.
Assertion (A) : There is no vaccine for AIDS. Reason (R) : The AIDS virus changes its genetic code.
  • A is true but R is false.
  • A is false but R is true.
  • Both A and R are false.
  • Both A and R are true and R is the correct explanation of A.
Explanation: 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.
Assertion (A) : Telephone wires sag more in summer. Reason (R) : They expand due to summer heat.
  • A is true but R is false.
  • A is false but R is true.
  • Both A and R are false.
  • Both A and R are true but R is not the correct explanation of A.
Explanation: 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.
Assertion (A) : An atom is neutral despite the charged particles in it. Reason (R) : The neutrons do not have any charge.
  • Both A and R are true but R is not the correct explanation of A.
  • Both A and R are true and R is the correct explanation of A.
  • A is false but R is true.
  • A is true but R is false.
Explanation: 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.
Assertion (A) : Clothes are not washed properly in hot water. Reason (R) : Hard water contains many minerals.
  • Both A and R are true but R is not the correct explanation of A.
    • Explanation: 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.