Molecular shape of SF₄, CF₄ and XeF₄ are

The hybridisation of atomic orbitals of nitrogen in $$NO_2^+$$, $$NO_3^-$$ and $$NH_4^+$$ are

For all $$x \in \left( {0,1} \right)$$

Let $$f\left( x \right) = \left\{ {\matrix{ {\left| x \right|,} & {for} & {0 < \left| x \right| \le 2} \cr {1,} & {for} & {x = 0} \cr } } \right.$$ then at $$x=0$$, $$f$$ has