If a solid contains some particles that melt at 50°c and other particles that melt at 110°c, what must be true about the solid?

If a solid contains some particles that melt at 50 degrees Celsius and other particles that melt at 110 degrees Celcius, the solid's actual melting point temperature must be near the higher melting point for the solid to be fully melted. It might start to melt at 50 - 110 degrees. 

The correct name for n3-ion should be azide.