Consider the molecular models below as proposed structures of hydrides of second-row elements. For each structure that is possible, identify the nonhydrogen atom and write the molecular formula.

Molecular models showing HF, BH3, and CH4 structures.

Molecular models showing HF, BeH2, and CH4 structures.

Molecular models of HF, BH3, CH4, and NH5.

Molecular models of HF, BH3, and H2O structures.