For an endothermic reaction:
∆rH is positive: Endothermic reactions absorb heat from the surroundings, resulting in a positive change in enthalpy (∆H).
\(q_p\) is positive: At constant pressure (denoted by the subscript p), the heat absorbed by the system (\(q_p\)) is equal to the change in enthalpy (∆H). Since ∆H is positive for an endothermic reaction, \(q_p\) is also positive.
Therefore, the correct statements are B and D.
A bob of heavy mass \(m\) is suspended by a light string of length \(l\). The bob is given a horizontal velocity \(v_0\) as shown in figure. If the string gets slack at some point P making an angle \( \theta \) from the horizontal, the ratio of the speed \(v\) of the bob at point P to its initial speed \(v_0\) is :