At what temperature does pure water melt under standard atmospheric pressure?

• A. 100~^ext{o}ext{C}
• B. 0~^ext{o}ext{C}
• C. -10~^ext{o}ext{C}
• D. 32~^ext{o}ext{C}

Answer: (B)

Verified step by step guidance

1. Understand that the melting point of a substance is the temperature at which it changes from solid to liquid under a given pressure, typically standard atmospheric pressure (1 atm).
2. Recall that for pure water at 1 atm pressure, the melting point is the temperature where ice (solid water) and liquid water coexist in equilibrium.
3. Recognize that the standard melting point of pure water is a well-established physical constant, commonly used as a reference point in temperature scales.
4. Identify that the melting point of pure water under standard atmospheric pressure is 0~^\text{o}~\text{C}, which means ice melts at 0 degrees Celsius.
5. Note that other temperatures given (such as 100~^\text{o}~\text{C}, -10~^\text{o}~\text{C}, and 32~^\text{o}~\text{C}) correspond to boiling point, below freezing, and the Fahrenheit freezing point respectively, but are not the melting point in Celsius.