Tap.
1. Aluminum can exist stably in the air, indicating that the activity of aluminum is not strong. Because copper is not very active, copper cannot react with a solution of silver nitrate to obtain metallic silver. （
2 Oxygen is used in steelmaking, one of the purposes of which is to remove excess carbon and other impurities from pig iron. （
3 At room temperature, the mass of the solution obtained after the full reaction of 1 g of magnesium and 1 g of dilute sulfuric acid is 2 g. （
4 Magnesium, iron, and copper can be compared with dilute hydrochloric acid, and dilute sulfuric acid can also be used to identify ** and copper. (
5 Metallic materials include pure metals and their alloys, alloys, synthetic fibers, and synthetic rubber are all synthetic materials. (
6 The metal resources in the earth's crust are all in the form of compounds. (
7 The hardness of the alloy is generally higher than that of the pure metal that composes it, so the hardness of steel is higher than that of pure iron, and copper-plated iron products are also an alloy. （
8 The alloy is harder than each of the metals that compose it, so lead-antimony alloys are usually used as fuses. (
9 Copper is used instead of silver because copper conducts electricity better than silver. (
10 There is a change in valency in the displacement reaction, and all reactions with a change in valency are displacement reactions. (
11 Aluminium products are corrosion-resistant because a dense film of alumina forms on their surface. (
12 The earth's metal resources are finite and non-renewable. (
13 The main principle of industrial ironmaking is the reaction of carbon with iron oxide at high temperatures. (
14 In the experiment of reducing iron oxide by carbon monoxide, carbon monoxide is applied after direct heating. (
15 The first product of industrial ironmaking is pig iron, and pig iron is pure. (
16 Preventing metal corrosion and finding metal substitutes are effective ways to protect metal resources. (
17 Iron rust is the process of slow oxidation of iron with oxygen and water in the air, and the principle of iron powder as a double absorbent and iron rust is the same when food is preservative. （
18 The rust produced by the reaction of iron with oxygen and water is very loose and cannot prevent the iron in the inner layer from continuing to react with oxygen and water, so all iron products can be corroded. (
19 Bicycle rain shelters made of steel frames in the school should be sprayed regularly to prevent rust. (
20 Waste batteries contain lead, nickel, cadmium, mercury and other metals, if these metals are used, not only can save metal resources, but also reduce environmental pollution. (