Melting point

2010-03-19 8:36 am

Melting point of oxides of P: 900
Melting point of oxides of Q: -90

Which of the following statement is correct?
A. The oxides of Q is a liquid at room temperature
B. Both P and Q are metals
C. The oxide of P conducts electricity in the solid state
D. The oxide of P is an ionic crystal

Please explain for each options. Thanks!

回答 (1)

Roy

2010-03-19 9:07 pm

✔ 最佳答案

D is correct since ionic compound(giant) has high melting,eg. 900.
since they are held by strong electrostatic force, so a large amount of energy is needed to break the bonds(to change the state)
C is not correct since ionic substance can not conduct electricity in solid state since there is no mobile e- or ions.but it can in molten state
B is not correct since no metal oxide has such a low melting pt.
A may not be correct since the boiling pt. should be lower than 24'c as its melting pt. is incredibly low, so it is a gas at room temp.

hope this can help you.

參考: myself

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