What is formed when sodium bicarbonate is heated strongly?

Which one of the following statements in regard to the excretion by the human kidneys is correct?

The correct order of increasing $s-$character (in percentage) in the hybrid orbitals of the following molecules/ions is:
$(I)$ $CO_3^{2-}$ $(II)$ $XeF_4$ $(III)$ $I_3^-$ $(IV)$ $NCl_3$ $(V)$ $BeCl_2$

The number of Barr bodies in a $XXXX$ female is .....

Which of the following statements is correct?

The function $f: R \rightarrow R$ defined by $f(x)=\frac{x}{\sqrt{1+x^2}}$ is ........