Pyrophosphoric acid : $H _{4} P _{2} O _{7}$
Let Oxidation state of $P$ be $x$$\Rightarrow 4 \times(+1)+2 x+7 \times(-2)=0$$\Rightarrow 4+2 x-14=0 $$\Rightarrow x=+5$
basicity of acid is four.
P block elements are those in which the last electron enters any of the three p-orbitals of their respective shells. Since a p-subshell has three degenerate p-orbitals each of which can accommodate two electrons, therefore in all there are six groups of p-block elements.
P block elements are shiny and usually a good conductor of electricity and heat as they have a tendency to lose an electron. You will find some amazing properties of elements in a P-block element like gallium. It’s a metal that can melt in the palm of your hand. Silicon is also one of the most important metalloids of the p-block group as it is an important component of glass.
