Acid-base chemistry worksheet with chemical formulas and reaction diagrams.

To solve this problem, we need to classify each chemical formula as an Acid, a Base, or a Salt. Here is a simple way to tell them apart:

1. Acids: Usually start with the letter H (Hydrogen).
* *Exception*: Some common acids like Acetic Acid ($HC_2H_3O_2$) might look different, but they still have H at the front or act like acids.
2. Bases: Usually end with OH (Hydroxide) or contain Ammonia ($NH_3$). They often have a metal at the start.
3. Salts: These are formed when an acid and a base react. They usually start with a Metal (like Na, K, Ca) or Ammonium ($NH_4$) and end with a non-metal part (like Cl, $SO_4$, $NO_3$). They do not start with H and do not end with OH.

Let's go through the list one by one:

1. HCl: Starts with H. -> Acid
2. NaOH: Ends with OH. -> Base
3. HI: Starts with H. -> Acid
4. KOH: Ends with OH. -> Base
5. PbBr: Starts with Metal (Pb), no H start, no OH end. -> Salt
6. H$_2$CO$_3$: Starts with H. -> Acid
7. Sr(OH)$_2$: Ends with OH. -> Base
8. RbCl: Starts with Metal (Rb). -> Salt
9. CaCl$_2$: Starts with Metal (Ca). -> Salt
10. H$_2$O: Water is neutral, but in these worksheets, it is often grouped with salts or left blank. However, strictly speaking, it is neither. But looking at standard keys for this level, if forced to choose, it's often considered a very weak amphoteric substance. Let's look closer. Actually, usually, water is just "Water". But if I must pick from Acid/Base/Salt, it doesn't fit well. Let's re-evaluate standard school contexts. Often, questions ask to identify A/B/S. Water is technically a very weak acid and base. However, in many simple keys, it might be skipped or labeled "Neutral". Let's look at item 23. It is also H2O. Let's assume for now it might be categorized loosely or perhaps the question implies identifying the *type* of compound. Wait, looking at #10 and #23, both are H2O. Let's stick to the strict definitions. If a student *must* circle one, it's tricky. But let's look at the others first.
*Self-Correction*: In many introductory chemistry contexts, if you *have* to label it, it's often treated as a neutral salt-like solvent or simply "Neutral". However, without a "Neutral" option, this is ambiguous. Let's look at similar online worksheets. Often, H2O is just identified as water. But if I must provide A, B, or S... actually, let's look at the pattern. Most items are clear. Let's mark it as Salt/Neutral contextually, but typically it's just Water. Let's see if there's a better fit. Actually, some curricula classify water as a very weak acid. But it's safer to note it's neutral. However, for the sake of a direct answer key format, I will label it based on the most common expectation: Neutral (or sometimes grouped with Salts as an ionic-like solvent, though it's covalent). Let's look at the provided solution space. It's a line. I will write "Neutral" if possible, but if restricted to A/B/S, it's a trick question. Let's assume the standard 3 categories. I will label it Salt (in the broad sense of being a product of neutralization, though technically incorrect) or leave it as Neutral. Let's check #23 again. Same thing. I will provide the most chemically accurate simple label: Neutral. If the teacher forces A/B/S, it's likely a trick. But wait, looking at #11 NaOH, that's a base. #12 H2SO4, acid.
*Refined Strategy*: I will label H2O as Neutral because it is neither an acid nor a base in the strong sense, nor a salt. If the user *must* pick one of the three, it's often considered a Salt in very simplified "product of reaction" models, but that's bad science. I'll stick with Neutral for accuracy, or note it. Actually, let's look at #19 NH4Cl. That's a salt. #20 Al(NO3)3. Salt.
Let's re-read the prompt image text: "Classify each of the following as an acid, a base or a salt." It does not offer "Neutral". This is a common flaw in worksheets. In such cases, Water is often accepted as Neutral. I will write Neutral for H2O.

11. NaOH: Ends with OH. -> Base
12. H$_2$SO$_4$: Starts with H. -> Acid
13. Mg(OH)$_2$: Ends with OH. -> Base
14. H$_3$PO$_4$: Starts with H. -> Acid
15. NH$_4$OH: Ends with OH (Ammonium Hydroxide). -> Base
16. CaCl$_2$: Starts with Metal (Ca). -> Salt
17. H$_2$S: Starts with H. -> Acid
18. Cr(OH)$_3$: Ends with OH. -> Base
19. NH$_4$Cl: Starts with Ammonium ($NH_4$), ends with Cl. No H start, no OH end. -> Salt
20. Al(NO$_3$)$_3$: Starts with Metal (Al). -> Salt
21. HNO$_3$: Starts with H. -> Acid
22. LiI: Starts with Metal (Li). -> Salt
23. H$_2$O: As discussed, chemically Neutral. If forced into A/B/S, it is amphoteric. I will list it as Neutral.
24. HI: Starts with H. -> Acid
25. Na$_2$Te: Starts with Metal (Na). -> Salt
26. Be(OH)$_2$: Ends with OH. -> Base

Let's double check #10 and #23. Is there any chance they are considered acids? H2O <-> H+ + OH-. It produces H+. But it also produces OH-. It's neutral. I will provide "Neutral" as the most honest answer, but add a note that if only A/B/S are allowed, it's a tricky question often marked as Neutral.

Wait, looking at #17 H2S. Hydrosulfuric acid. Yes, Acid.
Looking at #25 Na2Te. Sodium Telluride. Salt. Yes.

Final check of the list:
1. HCl - Acid
2. NaOH - Base
3. HI - Acid
4. KOH - Base
5. PbBr - Salt (Lead(II) bromide)
6. H2CO3 - Acid (Carbonic acid)
7. Sr(OH)2 - Base (Strontium hydroxide)
8. RbCl - Salt (Rubidium chloride)
9. CaCl2 - Salt (Calcium chloride)
10. H2O - Neutral (Water)
11. NaOH - Base
12. H2SO4 - Acid (Sulfuric acid)
13. Mg(OH)2 - Base (Magnesium hydroxide)
14. H3PO4 - Acid (Phosphoric acid)
15. NH4OH - Base (Ammonium hydroxide)
16. CaCl2 - Salt
17. H2S - Acid (Hydrosulfuric acid)
18. Cr(OH)3 - Base (Chromium(III) hydroxide)
19. NH4Cl - Salt (Ammonium chloride)
20. Al(NO3)3 - Salt (Aluminum nitrate)
21. HNO3 - Acid (Nitric acid)
22. LiI - Salt (Lithium iodide)
23. H2O - Neutral
24. HI - Acid
25. Na2Te - Salt
26. Be(OH)2 - Base (Beryllium hydroxide)

Note: For #10 and #23, since the worksheet asks for Acid, Base, or Salt, and Water is technically none (it's neutral/amphoteric), "Neutral" is the correct scientific classification. If your teacher strictly requires one of the three, they may consider it a very weak acid or base, but "Neutral" is the standard answer for water in this context.

Final Answer:
1. Acid
2. Base
3. Acid
4. Base
5. Salt
6. Acid
7. Base
8. Salt
9. Salt
10. Neutral (Water)
11. Base
12. Acid
13. Base
14. Acid
15. Base
16. Salt
17. Acid
18. Base
19. Salt
20. Salt
21. Acid
22. Salt
23. Neutral (Water)
24. Acid
25. Salt
26. Base