1. Is it possible to partially answer what you know about chromium? Select the correct statements

2. Are the following judgments about iron compounds correct? Choose the correct ones:
1) Iron(II) oxide is considered a basic oxide.
2) Iron(II) hydroxide exhibits amphoteric properties.
3) Heating iron filings with an alkaline melt of strong oxidizers results in ferrate.
4) Iron(II) hydroxide is a brown precipitate that remains stable upon standing.
5) Iron oxides dissolve in an ammonia solution.

3. An amphoteric oxide does not form a chemical element. Which one does not form hydrogen (H2) when interacting with chlorine:
1) Zinc
2) Silver
3) Magnesium
4) Chromium
5) Manganese

4. Which metal quickly oxidizes in humid air?
1) Zinc
2) Copper
3) Silver
4) Iron
5) Calcium

5. When reacting with chlorine, a compound with the composition ECl3 is formed by each of the two metals. Which pairs of metals form these compounds?
1) Chromium and Iron
2) Zinc and Copper
3) Copper and Iron
4) Aluminum and Zinc
5) Chromium and Aluminum

6. Zinc displaces a metal from a salt solution with the formula:
1) FeCl3
2) CrCl3
3) AlCl3
4) CaCl2
5) MgCl2

7. Hydrogen is not produced when zinc reacts with:
1) Steam
2) Concentrated sulfuric acid
3) Cold water
4) Sulfuric acid solution
5) Alkali solution

8. Which metal is passivated by concentrated nitric acid while diluted nitric acid reacts with it?
1) Zinc
2) Aluminum
3) Copper
4) Manganese
5) Iron

9. Out of the listed substances, which ones react with manganese:
1) NaOH
2) NaCl (aqueous)
3) H2
4) HCl (aqueous)
5) O2
6) Mg(NO3)2 (aqueous)

10. Which one does not react with metallic sodium:
1) Methane
2) Acetylene
3) Phenol
4) Aniline
5) Alanine

11. Establish a correspondence between salts and the flame color they produce:
SALT FLAME COLOR
A) Potassium salts B) Boric acid salts C) Lithium salts D) Sodium salts
1) Yellow 2) Orange 3) Green 4) Purple 5) Raspberry

12. Substances A and X are part of the transformation chain: Cl2 + NaOH + NaOH + HCl Cr → A → B → C → X
1) Cr(OH)3 2) Na3[Cr(OH)6] 3) CrCl3 4) CrCl2

13. Establish a correspondence between the salt name and the product of its hydrolysis in an aqueous solution:
SALT NAME PRODUCT AT THE CATHODE
A) Copper nitrate B) Iron(II) chloride C) Potassium chloride D) Copper hydrosulfate
1) Copper 2) Chlorine 3) Iron, Hydrogen 4) Hydrogen 5) Iron 6) Potassium

14. Establish a correspondence between the initial substances and the oxidation state of the metal in the reaction product:
INITIAL SUBSTANCES OXIDATION STATE
A) Copper(II) hydroxide and ethanal B) Chromium and sulfur C) Iron and oxygen D) Manganese and hydrochloric acid
1) +6 2) +2 3) +2, +3 4) +3 5) +1 6) +4

15. Iron weighing 11.2g was fused with sulfur weighing 9.6g. Hydrochloric acid (in excess) was added to the reaction product. The evolved gas was passed through a solution of copper(II) sulfate. Calculate the mass of the obtained precipitate if the yield was 85% of the theoretically possible amount. Answer: 16.32g.

16. Complete the reaction equation. Use the method of electronic balance to set the coefficients. Determine the oxidizing and reducing agents.
K2CrO4 + KNO2 + KOH + H2O → KNO3 + …

17. A sodium salt of yellow color weighing 6.48g was dissolved in water, and it was acidified with sulfuric acid, resulting in an orange solution. When an excess of potassium sulfite solution was added, a greenish-purple solution was formed. What is the mass of metallic chromium that can be obtained by electrolyzing the resulting solution? Answer: 2.08g.

18. Potassium chlorate was heated in the presence of a catalyst, producing a colorless gas. By burning iron in an atmosphere of this gas, iron slag was obtained. It was dissolved in dilute hydrochloric acid. To this resulting solution, a solution containing sodium dichromate and hydrochloric acid was added. Write the equations for the described reactions.

19. Potassium was fused with sulfur. The resulting salt was treated with hydrochloric acid. The gas released in this process was passed through a solution of potassium dichromate in sulfuric acid. The yellow precipitate obtained was filtered and fused with aluminum. Write the equations for the described reactions.