Which of the following is responsible for the production of biogas?

If $e$ and $e^{\prime}$ are the eccentricities of the ellipse $5x^2 + 9y^2 = 45$ and the hyperbola $5x^2 - 4y^2 = 45$ respectively,then $ee^{\prime}$ is equal to

The smallest positive root of the equation $\tan x - x = 0$ lies in the interval:

For $x \in \mathbb{R}$,the range of $3 \cos (4x - 5) + 4$ lies in the interval

If $4\,P(A) = 6\,P(B) = 10\,P(A \cap B) = 1,$ then $P\left( \frac{B}{A} \right) = $

Which oxide of manganese is amphoteric?