The percentage of gold in $14$ carat gold is: (in $\%$)

The focal length of an equi-convex lens is greater than the radius of curvature of any of the surfaces. Then the refractive index of the material of the lens is

If $f(x) = \begin{cases} x-5, & \text{for } x \leq 1 \\ 4x^2-9, & \text{for } 1 < x < 2 \\ 3x+4, & \text{for } x \geq 2 \end{cases}$,then $f^{\prime}(2^{+})$ is equal to

Approximately $70\%$ of carbon dioxide absorbed by the blood will be transported to the lungs:

What does the given figure represent?

Which one of the following is not a functional unit of an ecosystem?