The keys are based on contrasting characters generally in a pair called . . . . . . .

The position vectors of points $A, B, C$ and $D$ are $\vec A = 3\hat i + 4\hat j + 5\hat k, \vec B = 4\hat i + 5\hat j + 6\hat k, \vec C = 7\hat i + 9\hat j + 3\hat k$ and $\vec D = 4\hat i + 6\hat j$. Then the displacement vectors $\overrightarrow{AB}$ and $\overrightarrow{CD}$ are:

If $A, B$ and $C$ are any three sets,then $A - (B \cup C)$ is equal to

Resonance is an example of

The first diffraction minimum due to a single slit diffraction is seen at $\theta = 30^o$ for light of wavelength $5000 \, \mathring{A}$ falling perpendicularly on the slit. The width of the slit is

If $A=\left[\begin{array}{rr}i & -i \\ -i & i\end{array}\right]$ and $B=\left[\begin{array}{rr}1 & -1 \\ -1 & 1\end{array}\right]$,then find $A^8$. (in $B$)