Science Puzzle 1 - Free Printable

Let’s solve this science crossword puzzle step by step. We’ll go clue by clue, using what we know about basic science terms.

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ACROSS:

2. The process through which a substance changes from liquid to solid
→ That’s freezing. (Water turns to ice when it freezes.)

5. The centre of an atom is called ______
→ That’s the nucleus. (It holds protons and neutrons.)

7. Anything that has mass and occupies volume
→ That’s matter. (Everything around us — air, water, rocks — is matter.)

9. An indivisible and basic unit of matter
→ That’s an atom. (Atoms are the building blocks of everything.)

11. Positive ions are called ______
→ Those are cations. (When atoms lose electrons, they become positively charged.)

13. It is defined as mass divided by volume
→ That’s density. (Formula: density = mass / volume)

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DOWN:

1. Unit of measurement of time
→ Could be many things, but in crosswords, often second. (Basic SI unit for time.)

3. The mechanical process to separate solids from the fluids
→ That’s filtration. (Like using a coffee filter to separate grounds from liquid.)

4. A strong base that dissolves in water
→ Common example: lye or sodium hydroxide, but in simple puzzles, sometimes alkali fits. But let’s check length — if it’s 5 letters? Wait, looking at grid… Actually, common answer here is LYE — but let’s see intersections. Alternatively, “BASE” is too short. Hmm. Let’s hold and come back.

Wait — actually, in many school puzzles, they use ALKALI for this. But let’s check letter count from grid. Since we don’t have exact grid sizes visible, we’ll go with most common term: ALKALI (6 letters). Or maybe “CAUSTIC”? No. Let’s think again.

Actually, another possibility: SODA? Not quite. Best fit is ALKALI — but let’s verify with crossing clues later.

Alternatively — perhaps LIME? No. Let’s skip and come back.

6. It is the study of matter and the changes it undergoes
→ That’s chemistry. (Perfect fit.)

8. NH3
→ That’s ammonia. (Chemical formula for ammonia is NH₃.)

10. The only metal that is in liquid form at room temperature
→ That’s mercury. (Used in old thermometers.)

12. Blue litmus paper turns ______ under acidic conditions
→ Turns red. (Acids turn blue litmus red; bases turn red litmus blue.)

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Now let’s fill in Down #4 again: “A strong base that dissolves in water”

Common strong bases: Sodium hydroxide (NaOH), Potassium hydroxide (KOH) — but those are long. In simple puzzles, they might expect ALKALI — which is a general term for soluble bases.

But let’s check how many letters? From the grid layout (even though not fully visible), if Across 5 is “NUCLEUS” (7 letters), and Down 4 crosses it... Let’s assume standard answers.

Actually, another common answer is LYE — but that’s 3 letters. Maybe BASE? Too vague.

Wait — perhaps CAUSTIC? Still not perfect.

Hold on — let’s look at intersection points.

For example, Down 4 starts at top left area. If Across 2 is “FREEZING” (8 letters?), and Down 4 crosses it... This is tricky without seeing full grid.

But since this is a student-level puzzle, likely expected answers are:

Down 4 → ALKALI (if 6 letters) OR LYE (if 3). But let’s go with ALKALI as it’s more accurate scientifically for “strong base that dissolves in water”.

Alternatively — wait! Another possibility: SODIUM HYDROXIDE is too long. Perhaps the puzzle expects BASE? But that’s not specific.

Actually, re-reading: “A strong base that dissolves in water” — that’s literally the definition of an alkali. So yes, ALKALI is correct.

But let’s confirm spelling: A-L-K-A-L-I → 6 letters.

Now let’s list all answers clearly:

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Final Answers:

ACROSS:
2. FREEZING
5. NUCLEUS
7. MATTER
9. ATOM
11. CATIONS
13. DENSITY

DOWN:
1. SECOND
3. FILTRATION
4. ALKALI
6. CHEMISTRY
8. AMMONIA
10. MERCURY
12. RED

Wait — let’s double-check Down 1: “Unit of measurement of time” — could also be “MINUTE”, “HOUR”, etc. But “SECOND” is the SI base unit, so safest bet.

Also, Down 3: “The mechanical process to separate solids from the fluids” — definitely FILTRATION.

Down 8: NH3 → AMMONIA — correct.

Down 10: Liquid metal at room temp → MERCURY — correct.

Down 12: Blue litmus turns ___ in acid → RED — correct.

Across 11: Positive ions → CATIONS — correct.

Across 13: Mass/volume → DENSITY — correct.

All seem to fit.

One last check: Is there any conflict? For example, does “ALKALI” intersect correctly? Without seeing grid, we assume standard puzzle design.

Another thought: Sometimes for Down 4, they might accept “LYE”, but “ALKALI” is better scientifically.

Also, note: Across 9 is “ATOM” — 4 letters. Down 1 is “SECOND” — 6 letters. Seems okay.

I think we’re good.

Final Answer:
ACROSS: 2-FREEZING, 5-NUCLEUS, 7-MATTER, 9-ATOM, 11-CATIONS, 13-DENSITY
DOWN: 1-SECOND, 3-FILTRATION, 4-ALKALI, 6-CHEMISTRY, 8-AMMONIA, 10-MERCURY, 12-RED