Topic content:
Judging from your life experience and chemical knowledge, the following is correct ()
A. Wash the bike often with water to prevent rust.
B. Check whether the LPG in the cylinder leaks with a burning match.
C. Use dilute hydrochloric acid to remove scale (mainly calcium carbonate) from the kettle.
D. During class in winter, the doors and windows should be closed tightly to prevent cold air from entering the room.
Best answer:
C
Answer analysis:
Steel is easy to rust in wet environment, so it is wrong to wash bicycles with water frequently; Petroleum gas is easy to explode when encountering open fire. It is wrong to check whether the petroleum gas in the cylinder leaks with the burning match; In winter, closing doors and windows tightly in class is likely to cause indoor air turbidity, which is not conducive to health; Calcium carbonate can react with dilute hydrochloric acid to generate calcium chloride, water and carbon dioxide. C is correct. Select C.
Comment: All attention is knowledge, and chemistry is around us.
Test core:
The existence form of elements in human body:
① Carbon, hydrogen, oxygen and nitrogen mainly exist in the form of water, sugar, protein, vitamins and fat.
② Other elements mainly exist in aqueous solution in the form of inorganic salts.
③ Calcium element mainly exists in the form of hydroxycalcium phosphate [Ca10 (PO4) 6 (OH) 2] crystal.