The term for the distance between two crests of a water wave is the

Wavelength

Explanation:

A wave in general, is a disturbance that travels through a point in space. It is composed of a series of alternating peaks and valleys.

Peaks are points along the wave, where its amplitude or displacement from the rest position is maximum in a positive upward direction. These peaks are also referred to as 'crests'. Valleys or 'troughs' are points with maximum displacement in the negative downward direction.

In a water wave (or waves in general), the distance between two crests or peaks is referred to as the wavelength represented by the greek symbol, λ.

we can conclude that the melting point of table salt is above room temperature (it's actually 801 deg c). the melting point of mercury must be below room temperature (- 39 deg c).