Final answer:
The melting point of a substance is independent of the mass of the solid but is influenced by the intermolecular forces and pressure. Even if the mass changes, the melting point remains constant unless other external conditions like pressure are altered.
Step-by-step explanation:
The melting point of a substance does not depend on the mass of the solid placed in the capillary. Instead, the melting point is determined by the intermolecular forces within a substance and the energy required to overcome these forces. Even if you change the amount of substance by altering the mass, the temperature at which the solid transitions into a liquid phase remains the same. This principle applies to pure substances that have a clearly defined melting point.
Pressure, on the other hand, can affect the melting point. For example, ice will have a lower melting point under increased pressure, which is why applying pressure by squeezing a snowball or driving a car over snow can cause the ice to melt. However, adding more ice (increasing mass) will not alter the melting point provided the pressure remains constant.
Variations in melting point are rather related to changes in external conditions such as pressure, or intrinsic properties like the type and strength of intermolecular forces, which are reflected by factors such as molecular mass and the presence of London dispersion forces as mentioned in State of Matter Depends on the External Conditions and Summary sections.