Which one of the following salts gives an acidic solution in water?

The eccentricity of the ellipse $9x^2 + 5y^2 - 18x - 20y - 16 = 0$ is:

$A$ primary coil and a secondary coil are placed close to each other. $A$ current, which changes at the rate of $25 \, A$ in a millisecond, is present in the primary coil. If the mutual inductance is $92 \times 10^{-6} \, H$, then the value of the induced emf in the secondary coil is:

$\operatorname{sech}^{-1}(\sin \theta)$ is equal to

Which of the following is a linear molecule?

Which fungus has proven to be an effective biological control agent?