1．
根据下表的数据，判断下列说法的正确的是\(\rm{(}\) \(\rm{)}\)
| 离子化合物 | 电荷数
\(\rm{Z}\) | 键长
\(\rm{pm}\) | 晶格能
\(\rm{kJ⋅mol^{-1}}\) | 熔点
\(\rm{{\,\!}^{\circ}C}\) | 莫氏硬度 |
| \(\rm{NaF}\) | \(\rm{1}\) | \(\rm{231}\) | \(\rm{923}\) | \(\rm{993}\) | \(\rm{3.2}\) |
| \(\rm{NaCl}\) | \(\rm{1}\) | \(\rm{282}\) | \(\rm{786}\) | \(\rm{801}\) | \(\rm{2.5}\) |
| \(\rm{MgO}\) | \(\rm{2}\) | \(\rm{210}\) | \(\rm{3791}\) | \(\rm{2852}\) | \(\rm{6.5}\) |
| \(\rm{CaO}\) | \(\rm{2}\) | \(\rm{240}\) | \(\rm{3401}\) | \(\rm{2614}\) | \(\rm{4.5}\) |