Which property best indicates that a compound contains an ionic bond? it is insoluble in water. it can be easily flattened. it has a low boiling point. it conducts electricity when molten.

Answer is:  it conducts electricity when molten.

Ionic bond is the electrostatic attraction between oppositely charged ions (cations and anions).

Substances with ionic bond conduct an electric current in liquid, because in liquids ions are mobile, contrary to solids where ions are fixed.

For example, sodium chloride (NaCl) dissociates on ions when is molten:

NaCl(l) → Na⁺(l) + Cl⁻(l).

Compounds with the ionic bonds have high boiling points, because ionic bond is strong and they are mostly soluble in the water.

in cartography, a contour line (often just called a "contour") joins points of equal elevation (height) above a given level, such as mean sea level. a contour map is a map illustrated with contour lines, for example a topographic map, which thus shows valleys and hills, and the steepness or gentleness of slopes.

explanation:

periodic trends is an atom that gets larger as the number of electronic shells increase, the radius of atoms increases as you go down a certain group in the periodic table of elements. in general, the size of an atom will decrease as you move from left to right of a certain period.