Sexual reproduction leads to

$A$ spring $40\,mm$ long is stretched by the application of a force. If $10\,N$ force is required to stretch the spring through $1\,mm$,then work done in stretching the spring through $40\,mm$ is ............. $J$.

The value of $\int_{0}^{1} \left( \prod_{r=1}^{n} (x+r) \right) \left( \sum_{k=1}^{n} \frac{1}{x+k} \right) dx$ equals

Product $(A)$ is

If one of the lines in the pair of straight lines given by $4x^2+6xy+ky^2=0$ bisects the angle between the coordinate axes,then $k \in$

Which of the following is the strongest acid?