The Hill reaction takes place in which of the following conditions?

In non-cyclic photophosphorylation,how many protons $(H^+)$ are released into the lumen of the thylakoid for the photolysis of $2$ molecules of $H_2O$ (in $H^+$)?

Which of the following is the initiating step in photosynthesis?

Which of the following is the primary electron acceptor from the chlorophyll molecule of Photosystem-$II$?

Which of the following combinations is required for chemiosmosis?

Assertion $(A) : H^+$ gradient across the thylakoid membrane is essential for the formation of $\text{ATP}$.
Reason $(R) :$ Breakdown of $H^+$ gradient due to the movement of protons through $F_0$ of $\text{ATP}$ synthase releases enough energy to activate $\text{ATP}$ synthase enzyme that catalyses the formation of $\text{ATP}$.