1. Which of the following is one way to prevent the corrosion of iron?

A. Paint exposed iron parts with protective paint.
B. Protect the iron from polluted air.
C. Add carbon to the iron.
D. Let the iron develop a natural coat of carbonate.

2. The source of the sun's heat is
A. nuclear fusion.
B. nuclear disintegration.
C. nuclear separation.
D. nuclear fission.

3. Which of the following will result in a chemical change?
A. Drying wood in a shed
B. Evaporating alcohol into vapor
C. Melting ice to obtain water
D. Burning coal in a furnace

4. A solution that contains a small amount of salt and a large amount of water is said to be a _______ solution.
A. unsaturated
B. concentrated
C. saturated
D. dilute

5. Which one of the following is a characteristic of a metal?
A. Conducts heat readily
B. Changes the color of litmus paper to red
C. Reacts with bases to produce salts
D. Becomes negative when combined with other elements

6. Which one of the following chemical equations is balanced?
A. NH 3 + H2 O → 2NH4 OH
B. KOH + H2SO4 → KHSO4 + H2O C. 2Na + S → 2NaS
D. 2NaCl + H 2SO 4 → HCL + NaSO 4

7. A chemical reaction in which two or more substances undergo a chemical union to form a more complex substance is a _______ reaction.
A. substitution
B. combination
C. double replacement
D. decomposition

8. In a nuclear reaction, energy is released by the combination of two elements into a new element. This process is an example of
A. natural radioactivity.
B. nuclear fusion.
C. nuclear fission.
D. artificial disintegration.

9. An atom of chlorine has several valence electrons in its
A. first shell.
B. second shell.
C. third shell.
D. nucleus.

10. A chemical reaction in which two elements or radicals change places with two other elements or radicals is a _______ reaction.
A. decomposition
B. combination
C. substitution
D. double replacement

11. The valence of aluminum is +3, and the valence of chlorine is –1. The formula for aluminum chloride is correctly written as
A. AlCl3.
B. Al 3Cl.
C. ClAl3.
D. Cl3 Al.

12. The molecular mass of sodium oxide (Na 2 O) is
A. 22.98977.
B. 45.97954.
C. 61.97894.
D. 38.98917.

13. A salt is obtained as a reaction between
A. an acid and oxygen.
B. a base and an acid.
C. a nonmetal and a metal.
D. a base and water.

14. Which of the following is represented in the highest percentage by volume in dry air?
A. Carbon dioxide
B. Hydrogen
C. Nitrogen
D. Oxygen

15. The process of splitting an atom into two lighter atoms is called
A. nuclear fission.
B. nuclear fusion.
C. nuclear separation.
D. nuclear disintegration.

16. The factor that affects how easily an electron can be removed from an atom is the
A. temperature of the environment.
B. structure of the atom.
C. size of the atom.
D. surrounding atoms.

17. A solution that contains a large amount of salt and a small amount of water is said to be a _______ solution.
A. dilute
B. unsaturated
C. concentrated
D. saturated

18. The element fluorine is classified in the periodic table as a/an
A. alkali metal.
B. metalloid.
C. metal.
D. halogen.

19. A chemical reaction in which compounds break up into simpler constituents is a _______ reaction.
A. double replacement
B. combination
C. decomposition
D. substitution

20. _______ are atoms that carry an electric charge.
A. Nonelectrolytes
B. Ions
C. Colloids
D. Electrolytes

21. A substance that contains hydrogen that may be replaced by a metal is a/an
A. nonmetal.
B. base.
C. acid.
D. colloid.

22. Which one of the following statements about sulfuric acid is correct?
A. Sulfuric acid is a strong oxidizing agent.
B. Sulfuric acid is dangerous to living organisms.
C. Sulfuric acid is a known muriatic acid.
D. Sulfuric acid has little effect on metals.

23. Which of the following elements is stable?
A. Carbon, atomic number 6
B. Neon, atomic number 10
C. Fluorine, atomic number 9
D. Boron, atomic number 5

24. The measure of the number of atoms in one element that will combine with an atom of another element is
A. atomic charge.
B. molecular number.
C. atomic number.
D. valence.

25. The primary metallic element that's added to steel to make stainless steel is
A. silver.
B. antimony.
C. chromium.
D. tungsten.

1. A

2. A
3. D
4. D
5. A
6. B
7. B
8. B
9. C
10. D
11. A
12. C
13. B
14. C
15. A
16. B
17. C
18. D
19. C
20. B
21. C
22. B
23. B
24. D
25. C

I checked the first ten, all ok.

4 is C

Wow, that's a lot of questions

1. To prevent the corrosion of iron, one way is to paint exposed iron parts with protective paint. This creates a barrier between the iron and the external environment, preventing contact with moisture and oxygen, which are the main causes of corrosion.

2. The source of the sun's heat is nuclear fusion. Nuclear fusion occurs in the core of the sun, where hydrogen atoms combine to form helium, releasing a tremendous amount of energy in the process.

3. Burning coal in a furnace will result in a chemical change. Burning is a chemical reaction in which a substance combines with oxygen to produce new substances with different properties. In the case of burning coal, it produces carbon dioxide, water vapor, and various other byproducts.

4. A solution that contains a small amount of salt and a large amount of water is said to be a dilute solution. In a dilute solution, the concentration of the solute (in this case, salt) is low compared to the amount of solvent (water).

5. A characteristic of a metal is that it conducts heat readily. Metals have high thermal conductivity, which means they can transfer heat quickly and efficiently.

6. The chemical equation "2Na + S → 2NaS" is balanced. A balanced chemical equation has an equal number of atoms of each element on both sides of the equation.

7. A chemical reaction in which two or more substances undergo a chemical union to form a more complex substance is a combination reaction. In a combination reaction, the reactants combine to form a single product.

8. The combination of two elements into a new element, releasing energy, is an example of nuclear fusion. Nuclear fusion is the process in which two or more atomic nuclei collide and combine to form a larger nucleus, releasing a tremendous amount of energy.

9. An atom of chlorine has several valence electrons in its third shell. The valence electrons are the electrons in the outermost shell of an atom, and they are involved in chemical bonding.

10. A chemical reaction in which two elements or radicals change places with two other elements or radicals is a double replacement reaction. In a double replacement reaction, the cations and anions of two compounds switch places to form two new compounds.

11. The formula for aluminum chloride is correctly written as AlCl3. The valence of aluminum is +3, and the valence of chlorine is -1. To balance the charges, three chlorine atoms are needed for every one aluminum atom.

12. The molecular mass of sodium oxide (Na2O) is 61.97894. The molecular mass is calculated by adding up the atomic masses of all the atoms in the formula.

13. A salt is obtained as a reaction between a base and an acid. When a base reacts with an acid, they undergo a neutralization reaction, producing a salt and water as products.

14. Nitrogen is represented in the highest percentage by volume in dry air. Dry air is mainly composed of nitrogen, oxygen, and small amounts of other gases.

15. The process of splitting an atom into two lighter atoms is called nuclear fission. Nuclear fission involves the breaking apart of a heavy nucleus into two or more smaller nuclei, releasing a large amount of energy.

16. The factor that affects how easily an electron can be removed from an atom is the structure of the atom. The arrangement of electrons in the atom's energy levels and the attraction between the protons in the nucleus and the electrons play a role in determining the ionization energy.

17. A solution that contains a large amount of salt and a small amount of water is said to be a concentrated solution. In a concentrated solution, the concentration of the solute is high compared to the amount of solvent.

18. The element fluorine is classified in the periodic table as a halogen. Halogens are a group of elements that are highly reactive nonmetals.

19. A chemical reaction in which compounds break up into simpler constituents is a decomposition reaction. In a decomposition reaction, a compound breaks down into two or more simpler substances.

20. Ions are atoms that carry an electric charge. When an atom gains or loses electrons, it becomes an ion and acquires either a positive or negative charge.

21. A substance that contains hydrogen that may be replaced by a metal is an acid. Acids are substances that can donate hydrogen ions (H+) in a chemical reaction.

22. Sulfuric acid is dangerous to living organisms. It is a strong acid that can cause severe burns and is highly corrosive to many materials, including metals.

23. Neon, atomic number 10, is stable. Stability in this context refers to the fact that the nucleus of neon does not undergo spontaneous radioactive decay.

24. The measure of the number of atoms in one element that will combine with an atom of another element is valence. Valence is a measure of the combining capacity of an atom, indicating the number of bonds it can form with other atoms.

25. The primary metallic element that's added to steel to make stainless steel is chromium. Chromium increases the corrosion resistance of steel and gives stainless steel its characteristic properties.