Question

For an endothermic reaction:
(A) \( q_p \) is negative.
(B) \( \Delta_rH \) is positive.
(C) \( \Delta_rH \) is negative.
(D) \( q_p \) is positive.
Choose the correct answer from the options given below:

• A. B and D
• B. C and D
• C. A and B
• D. A and C

Answer 1

The Correct Option is A

An endothermic reaction is characterized by the absorption of heat from the surroundings, resulting in a positive change in enthalpy. Let us analyze the options given:

• (A) \( q_p \) is negative: For an endothermic reaction, the heat absorbed at constant pressure \( q_p \) is positive because the system absorbs heat. Therefore, this option is incorrect.
• (B) \(\Delta_rH\) is positive: The change in enthalpy \(\Delta_rH\) for an endothermic reaction is indeed positive because the system absorbs energy. Hence, this option is correct.
• (C) \(\Delta_rH\) is negative: A negative change in enthalpy would indicate an exothermic reaction where heat is released, not absorbed. Thus, this option is incorrect for an endothermic reaction.
• (D) \( q_p \) is positive: As previously explained, for an endothermic reaction, \( q_p \) is positive, confirming this option as correct.

Therefore, the correct answer is option B and D, as \(\Delta_rH\) is positive and \( q_p \) is positive for an endothermic reaction.