(a) Explain pure lead melts at 327oC and pure tin melts at 232o C, yet while we make an alloy of lead-61.9 wt% Sn it melts at a much lower temperature of 183oC, explain.
(b) Explain pure lead freezes at one constant temperature of 327oC, yet the lead- 30 wt% Sn alloy freezes over a 60 oC temperature range, explain.