Materials are the important material basis for human existence, and chemistry is the basis for the development of materials science. Please fill in the following blanks. ① Ceramics and cement in life.

① Glass, ceramics and cement are three traditional inorganic silicate materials;

The raw materials for producing glass are soda ash, limestone and timely; The raw material for producing ceramics is clay, and limestone is not needed; Clay and limestone are the main raw materials for producing cement;

So the answer is: glass; Ceramics;

(2) It is judged that sodium and potassium are solid at room temperature, while the alloy is liquid at room temperature, indicating that the melting point of the alloy is lower than that of its constituent metals.

So, the answer is: low;

③ A. Covering the outside with a layer of plastic can reduce the contact with oxygen in the air and prevent the metal from being chemically corroded, so A is correct;

B plating a layer of chromium can isolate the air and prevent it from contacting with oxygen in the air and causing chemical corrosion, so B is correct;

C. The activity of iron is stronger than that of copper, forming primary battery iron as the negative electrode, which leads to oxidation reaction and accelerates the corrosion of iron, so C is wrong;

So choose: C.