Fill in the blanks 1. Metals like on ______exposure to moisture develop a greenish coating.
2. Magnesium reacts with _______and forms magnesium oxide and liberates gas.
3 In a reaction, formation of hydrogen gas is indicated by ______ sound.
4 The _______ oxides turn blue litmus red.
5._____ is the least reactive metal. 6. Copper does not ______zinc from its salt solution.
Answers
1. Metals like copper on exposure to moisture develop a greenish coating.
Copper, when exposed to moisture, develops a greenish coating because of a natural process in metals called 'corrosion'. Most metals get corroded due to contact with air and water, for example, iron and aluminium. Gold, silver and platinum are noble metals, because they do not get corroded easily due to their less reactive nature.
2. Magnesium reacts with oxygen and forms magnesium oxide and liberates gas.
The reaction between magnesium and oxygen produces a big amount of light and heat. The reaction could be inferred with the following equation:
3. In a reaction, formation of hydrogen gas is indicated by pop sound.
When a reaction takes place, a slight pop sound shows the presence of hydrogen gas. Hydrogen makes this sound because of its reaction with oxygen in the air.
4 The sulfur and iron oxides turn blue litmus red.
The turning of blue litmus red indicates that the substance is acidic. Sulfur and iron oxides are some examples that are acidic oxides.
5. Platinum is the least reactive metal.
Platinum is the least reactive metal because it does not highly react with oxygen or water, unlike other reactive metals. This is why platinum is used in making jewelry.
6. Copper does not displace zinc from its salt solution.
The type of reaction in which a more reactive metal displaces a less reactive metal from its salt solution is called displacement. As copper is less reactive a metal than zinc, it cannot displace zinc, a more reactive metal, from its salt solution.