What is the oxidation number of phosphorus in calcium phosphate?

Which of the following forms 2-Methylbut-2-ene on heating with concentrated sulphuric acid?

If $\mathrm{E}^{\circ}\left(\mathrm{Zn}_{(\mathrm{aq})}^{+2} \mid \mathrm{Zn}_{(\mathrm{s})}\right)=-0.76 \mathrm{~V}$.

Calculate potential for $\mathrm{Zn}_{(\mathrm{s})} \rightarrow \mathrm{Zn}^{+2}(0.01 \mathrm{M})+2 \mathrm{e}^{-}$at 298 K .

Which among the following is NOT dicarboxylic acid?