The organelle associated with aerobic respiration is:

$A$ radioactive nucleus (initial mass number $A$ and atomic number $Z$) emits $3 \,\alpha-$ particles and $2$ positrons. The ratio of the number of neutrons to that of protons in the final nucleus will be:

In an astronomical telescope in normal adjustment,a straight black line of length $L$ is drawn on the inside part of the objective lens. The eyepiece forms a real image of this line. The length of this image is $I$. The magnification of the telescope is

If the standard deviation of the numbers $-1, 0, 1, k$ is $\sqrt{5}$ where $k > 0,$ then $k$ is equal to

If a body is projected with an angle $\theta$ to the horizontal,then

The minimum value of $27 \tan ^2 \theta + 3 \cot ^2 \theta$ is