consider a water molecule and substitute one hydrogen atom with deuterium. dose the structure change?

Can someone me with questions 12 and 13 plz.

The table compares the number of electrons in two unknown neutral atoms. comparison of electrons atom number of electrons a 10 d 11 use this information to determine the number of valence electrons in the atoms. which of the following correctly compares the stability of the two atoms? both are unreactive. both are highly reactive. a is unreactive and d is reactive. a is reactive and d is unreactive.

What is the percentage of hydrogen in nitrogen trihydride