The phase difference between input and output voltage of a $CE$ circuit is.......$^o$

Let $f$ be a differentiable function such that $f(1)=2$ and $f^{\prime}(x)=f(x)$,for all $x \in \mathbb{R}$. If $h(x)=f(f(x))$,then $h^{\prime}(1)$ is equal to

Three charges $2q, -q$ and $-q$ are located at the vertices of an equilateral triangle. At the centre of the triangle,

$A$ curve satisfying the initial condition,$y(1) = 0,$ satisfies the differential equation,$x \frac{dy}{dx} = y - x^2.$ The area bounded by the curve and the $x$-axis is

$A$ block of mass $m$ is at rest on another block of the same mass as shown in the figure. The lower block is attached to a spring. What is the maximum amplitude of motion so that both blocks remain in contact?

Which of the following statements is consistent with the Kingdom Fungi?