Free Printable Acids Bases and Salts Worksheets - Free Printable

Let's go through each question one by one and solve them with explanations.

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1) Which one of the following is acidic?
a) Lemon juice
b) Tomato
c) Milk
d) All

✔ Answer: d) All

Explanation:
- Lemon juice contains citric acid → acidic
- Tomatoes contain citric and malic acids → acidic
- Milk has lactic acid → slightly acidic (pH around 6.5–6.7)
So, all three are acidic in nature.

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2) Which one of the following will turn red litmus blue?
a) Vinegar
b) Baking soda
c) Lemon juice
d) Soft drinks

✔ Answer: b) Baking soda

Explanation:
Red litmus turns blue in basic solutions.
- Vinegar = acidic → no change
- Lemon juice = acidic → no change
- Soft drinks = acidic (due to carbonic acid) → no change
- Baking soda (sodium bicarbonate) = basic → turns red litmus blue

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3) Which one of the following will turn blue litmus red?
a) Vinegar
b) Lime water
c) Baking soda solution
d) Washing soda solution

✔ Answer: a) Vinegar

Explanation:
Blue litmus turns red in acidic solutions.
- Vinegar = acetic acid → acidic → turns blue litmus red
- Lime water = Ca(OH)₂ → basic → no change
- Baking soda & washing soda = both basic → no change

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4) Lime water is
a) CaO
b) Ca(OH)₂
c) CaCO₃
d) CaCl₂

✔ Answer: b) Ca(OH)₂

Explanation:
Lime water is a solution of calcium hydroxide, Ca(OH)₂, in water. It's used to test for CO₂.

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5) A compound that turns lime water into colorless again when excess carbon dioxide is made to pass through it is
a) Calcium carbonate
b) Calcium bicarbonate
c) Calcium oxide
d) Calcium hydroxide

✔ Answer: b) Calcium bicarbonate

Explanation:
When CO₂ is passed through lime water (Ca(OH)₂), it first forms calcium carbonate (CaCO₃), which is insoluble and makes the solution milky.
With excess CO₂, calcium carbonate reacts further to form soluble calcium bicarbonate (Ca(HCO₃)₂), which dissolves and makes the solution clear again.

Reaction:
1. Ca(OH)₂ + CO₂ → CaCO₃↓ (milky) + H₂O
2. CaCO₃ + CO₂ + H₂O → Ca(HCO₃)₂ (clear)

So, the compound formed that makes it colorless is calcium bicarbonate.

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6) Which among the following is an alkali oxide?
a) Carbon dioxide
b) Sulfur dioxide
c) Sodium oxide
d) Nitrogen oxide

✔ Answer: c) Sodium oxide

Explanation:
Alkali oxides are metal oxides that react with water to form alkalis (bases).
- Sodium oxide (Na₂O) + H₂O → 2NaOH (strong base) → Alkali oxide
Others:
- CO₂, SO₂, NO → non-metal oxides → acidic or neutral → not alkali oxides

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7) What gas is liberated when dilute sulfuric acid reacts with zinc granules?
a) Sulfur dioxide
b) Carbon dioxide
c) Nitrogen
d) Hydrogen

✔ Answer: d) Hydrogen

Explanation:
Metals like zinc react with dilute acids to produce hydrogen gas.

Zn + H₂SO₄ → ZnSO₄ + H₂↑

This is a typical displacement reaction where hydrogen gas is evolved.

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8) A solution reacts with crushed eggshells and releases a gas that turns lime water milky. The solution contains
a) NaCl
b) HCl
c) LiCl
d) KCl

✔ Answer: b) HCl

Explanation:
Eggshells are made of calcium carbonate (CaCO₃).
When reacted with an acid, it produces carbon dioxide (CO₂) gas:

CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂↑

CO₂ turns lime water milky (forms CaCO₃ precipitate).
Only acids can do this. Among the options, only HCl is an acid.
NaCl, LiCl, KCl are salts and neutral — they won’t react with CaCO₃.

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✔ Final Answers:

1) d) All
2) b) Baking soda
3) a) Vinegar
4) b) Ca(OH)₂
5) b) Calcium bicarbonate
6) c) Sodium oxide
7) d) Hydrogen
8) b) HCl

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