Steam Boilers, Engines, Nozzles and Turbines
For water, at pressures below atmospheric;

Melting point drops slightly and boiling point drops markedly
Melting point rises slightly and boiling point drops markedly
Melting point drops slightly and boiling point drops slightly
Melting point rises markedly and boiling point drops markedly

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Steam Boilers, Engines, Nozzles and Turbines
Spontaneous combustion is a phenomenon in which

Fuel burns with less air
Explosion in furnace
Coal bursts into flame without any external ignition source but by itself due to gradual increase in temperature as a result of heat released by combination of oxygen with coal
All the fuel burns instantaneously producing high energy release

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