Which is an excellent insulator even when molten or dissolved in water ()
A. Metallic Crystals
B. Ionic Crystals
C. Molecular Crystals
D. Atomic Crystals
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The mathematical treatment of of () is particularly difficult to develop.
A. solid
B. liquid
C. gas
D. molten
K ion has an oxidation number of ()
A. +1
B. +2
C. 0
D. -1
Choose the right characterization of hydrogen()
A. 氢元素与氢原子表述为hydrogen,氢气的表述为bihydrogen。
B. 氢元素与氢原子表述为hydrogen,氢气的表述为dihydrogen。
C. 氢元素与氢原子表述为hydrogen,氢气的表述为hydrogens。
D. 氢元素、氢原子与氢气的表述都为hydrogen。
Choose the right characterization ()
A. Group 2 elements are called "alkali metals".
B. Graphite is one of the hardest known materials.
C. Lithium is a Group 1 element containing just a single valence electron.
D. Helium gas is diatomic gas.
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