In which of the following pairs of categories is it more difficult to determine the relationship to other taxa at the same level, thus making the problem of classification more complex?

When current in a coil changes from $5\,A$ to $2\,A$ in $0.1\,s$,an average voltage of $50\,V$ is produced. The self-inductance of the coil is $............H$.

The load versus elongation graph for four wires of the same material is shown in the figure. The thickest wire is represented by the line

Identify the figure:

The plates of a parallel plate capacitor are charged up to $100\, V$. $A$ $2\, mm$ thick plate is inserted between the plates. To maintain the same potential difference,the distance between the capacitor plates is increased by $1.6\, mm$. The dielectric constant of the plate is:

What is the value of linear velocity,if $\vec \omega = 3\hat i - 4\hat j + \hat k$ and $\vec r = 5\hat i - 6\hat j + 6\hat k$?