The rank of the matrix$$\left[ {\matrix{ 1 & 1 \cr 0 & 0 \cr } } \right]\,\,is$$

The binary relation $$S = \phi $$ (emply set) on set A = {1, 2, 3} is

The minimum number of colors required to color the vertices of a cycle with $$n$$ nodes in such a way that no two adjacent nodes have the same colour is:

Four fair coins are tossed simultaneously. The probability that at least one head and one tail turn up is