Under which conditions is `(xy)/(x-y)` negative?

Under which of the following conditions is (x(x-y))/(y) negative?

Under which of these conditions there is no need for emasculation?

Under which of the following sets of conditions, DeltaG is always negative?

Which of the following ions if reduced under standard conditions, will have negative reduction potential-

Which of the following ions if reduced under standard conditions, will have negative reduction potential-

Under what conditions will a reaction be spontaneous if (i) both DeltaH and DeltaS are positive? (ii) both DeltaH and DeltaS are negative?

Under what conditions will a convex lens have a negative and a concave lens a positive power?

Under which conditions will cyclic photophosphorylation occur?