Importance of day length in flowering of plants was first shown in

$A$ particle of mass $5 \times 10^{-5} \ kg$ is placed at the lowest point of a smooth parabola $x^2 = 40y$ (where $x$ and $y$ are in $m$). If it is displaced slightly such that it is constrained to move along the parabola,the angular frequency of oscillation (in $rad/s$) will be approximately:

The Bhopal gas tragedy of $1984$ was caused by:

Explain the reason for the fusion of an organic compound with metallic sodium for testing nitrogen,sulphur and halogens.

In each of the following,determine whether the statement is true or false. If it is true,prove it. If it is false,give a counterexample.
If $x \in A$ and $A \in B,$ then $x \in B$.

Which one of the following statements is $WRONG$ in the context of $X-$rays generated from an $X-$ray tube?