The blank is the temperature at which a material changes from a liquid to a gas while the blank is the temperature at which a material changes from a solid to a liquid

Liquid to gas - Above 100 degrees Celsius, or 212 degrees Fahrenheit, water changes its phase into a gas called water vapor.

Solid to liquid - melting point of a solid is the same as the freezing point of the liquid. At that temperature, the solid and liquid states of the substance are in equilibrium. For water, this equilibrium occurs at 0°C.

1) according to the law of conservation of mass ,in all chemical reactions total mass is unchanged

It is a body of knowledge gained  using  inquiry and experimentation