Class 8 Chemistry Worksheet on Chapter 4 Materials: Metals and Non ... - Free Printable

Let's solve each question from the Chemistry Worksheet for Class 8 – Chapter 4: Metals and Non-metals step by step.

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Q-1: Which of the following is not a characteristic of metals?

Options:
a) Can be drawn into wires
b) Generally hard
c) Produces stillness when dropped
d) Shiny appearance

✔ Answer: c) produces stillness when dropped

Explanation:
Metals have several physical properties like:
- Malleability (can be hammered into sheets)
- Ductility (can be drawn into wires) → Option a ✔
- Hardness → Option b ✔
- Lustre (shiny appearance) → Option d ✔

However, "produces stillness when dropped" is not a property of metals. In fact, metals usually produce a ringing sound when struck or dropped — this is called sonority, which is a characteristic of metals.

So, option c is incorrect, making it the correct answer to this question.

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Q-2: Which of the following statements is not correct?

Options:
a) Iron is a metal and it reacts with water vigorously
b) Reactions of non-metals with base are complex
c) Non-metallic oxides are acidic and metallic oxides are basic
d) Sodium metal cannot be kept in the open air

✔ Answer: a) Iron is a metal and it reacts with water vigorously

Explanation:
Let’s analyze each option:

- a) Iron is a metal, but it does not react vigorously with water. It reacts slowly with steam to form iron(II,III) oxide and hydrogen gas:
$$
3Fe + 4H_2O(g) \rightarrow Fe_3O_4 + 4H_2
$$
So, this statement is false → Incorrect statement → This is the correct choice.

- b) Non-metals can react with bases in complex ways (e.g., chlorine reacts with NaOH). This is true.

- c) True: Non-metallic oxides (like CO₂, SO₂) form acids in water; metallic oxides (like Na₂O, CaO) form bases.

- d) Sodium is highly reactive with moisture and oxygen in air → must be stored under kerosene or oil. So, cannot be kept in open air → True.

Thus, option a is not correct, so it is the answer.

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Q-3: Which of the following metal/non-metal is stored in water?

Options:
a) Na
b) K
c) S
d) P

✔ Answer: a) Na (Sodium)

Wait — actually, let's clarify:

- Sodium (Na) and Potassium (K) are both very reactive metals.
- They react violently with water:
$$
2Na + 2H_2O \rightarrow 2NaOH + H_2
$$
So, they cannot be stored in water — they are stored in kerosene.

- Sulfur (S) and Phosphorus (P) are non-metals.
- White phosphorus is stored in water because it ignites spontaneously in air.
- Sulfur is stable in air and doesn't need special storage.

So, white phosphorus (P) is stored in water to prevent oxidation and spontaneous combustion.

But the options say:
> a) Na
> b) K
> c) S
> d) P

So, only P (phosphorus) is stored in water.

✔ Correct Answer: d) P

Note: This may seem confusing because sodium and potassium are often associated with storage issues, but they are stored in kerosene, not water.

Phosphorus (especially white P) is stored under water to prevent exposure to air.

So, d) P is the correct answer.

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Q-4: Fill in the table

We are given some acids/bases and asked to identify the corresponding non-metal or metal, and fill in missing values.

| S.No | Chemical formula of the acid | Non-metal | Chemical formula of the base | Metal |
|------|-------------------------------|-----------|------------------------------|-------|
| 1. | H₃PO₄ | | Na₂O | |
| 2. | | Carbon | | Potassium |
| 3. | H₂SO₄ | | NH₄OH | |
| 4. | HCl | | | Magnesium |
| 5. | | Nitrogen | Fe₂O₅ | |

Let’s go row by row.

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#### Row 1:
- Acid: H₃PO₄ → Phosphoric acid → comes from phosphorus (P) → Non-metal: Phosphorus
- Base: Na₂O → Sodium oxide → from sodium (Na) → Metal: Sodium

✔ So:
- Non-metal: Phosphorus
- Metal: Sodium

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#### Row 2:
- Non-metal: Carbon
- Metal: Potassium
- So, acid formed from carbon → Carbonic acid (H₂CO₃)
- Base from potassium → KOH (potassium hydroxide)

✔ So:
- Acid: H₂CO₃
- Base: KOH

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#### Row 3:
- Acid: H₂SO₄ → Sulfuric acid → from sulfur (S) → Non-metal: Sulfur
- Base: NH₄OH → Ammonium hydroxide → from nitrogen (N) → Non-metal: Nitrogen
But wait — NH₄OH is not a metal base. It's an ammonium compound, but nitrogen is a non-metal.

But the table asks for metal in the last column. However, NH₄OH is not derived from a metal. So there's an issue.

Wait — perhaps we need to interpret:

- The base NH₄OH is formed from ammonia (NH₃), which contains nitrogen.
- But no metal is involved here.

But the table has "Metal" column — maybe it's expecting no metal?

Alternatively, maybe the base should be associated with a metal, but NH₄OH is not a typical metal hydroxide.

Let’s re-evaluate:

Perhaps the base NH₄OH is not from a metal. So no metal is present.

But the structure suggests that for every row, either the acid or base comes from a non-metal or metal.

Let’s try again.

Wait — perhaps the acid H₂SO₄ comes from sulfur (non-metal), and the base NH₄OH comes from nitrogen (non-metal), so no metal.

But the metal column is blank — so maybe it's not applicable.

But the instruction says: "identify the metal or nonmetal present in them that forms oxides with oxygen"

So, for H₂SO₄, sulfur forms SO₃ → SO₃ + H₂O → H₂SO₄

For NH₄OH, it's not a metal hydroxide — it's ammonia dissolved in water.

So likely, no metal is involved here.

But maybe the metal column is meant for the base if it's a metal hydroxide.

Wait — let’s look at Row 4:

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#### Row 4:
- Acid: HCl → Hydrochloric acid → from chlorine (Cl) → Non-metal: Chlorine
- Metal: Magnesium → forms Mg(OH)₂ → base
- So base = Mg(OH)₂

✔ So:
- Non-metal: Chlorine
- Base: Mg(OH)₂

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#### Row 5:
- Non-metal: Nitrogen
- Base: Fe₂O₅ → Wait! Fe₂O₅ is not a standard compound.

Actually, iron forms Fe₂O₃ (rust), not Fe₂O₅.

Possibly a typo — Fe₂O₃ is common.

But Fe₂O₅ isn’t valid. Let’s assume it’s Fe₂O₃.

- Fe₂O₃ is iron(III) oxide → from iron (Fe) → Metal: Iron
- Nitrogen forms N₂O₅, which gives HNO₃ (nitric acid)

So:
- Acid from nitrogen: HNO₃
- Base from iron: Fe(OH)₃

But the table says:
- Base: Fe₂O₅ → invalid

Wait — perhaps it's Fe₂O₃ instead of Fe₂O₅.

Maybe Fe₂O₅ is a mistake. Likely, it should be Fe₂O₃.

Assuming that, then:

- Base: Fe₂O₃ → from Iron (Fe) → Metal: Iron
- Acid from nitrogen: HNO₃

So:
- Acid: HNO₃
- Metal: Iron

Now let’s fill the full table.

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Final Table:

| S.No | Chemical formula of the acid | Non-metal | Chemical formula of the base | Metal |
|------|-------------------------------|-----------|------------------------------|-------|
| 1. | H₃PO₄ | Phosphorus | Na₂O | Sodium |
| 2. | H₂CO₃ | Carbon | KOH | Potassium |
| 3. | H₂SO₄ | Sulfur | NH₄OH | — (No metal) |
| 4. | HCl | Chlorine | Mg(OH)₂ | Magnesium |
| 5. | HNO₃ | Nitrogen | Fe₂O₃ (assumed) | Iron |

But in Row 3, NH₄OH is not a metal hydroxide — so no metal is listed.

But the table has a "Metal" column — maybe it's left blank.

Alternatively, perhaps NH₄OH is considered as coming from ammonium ion, but no metal.

So, we’ll leave Metal blank for Row 3.

But let’s double-check the original table.

Original:

| S.No | Chemical formula of the acid | Non-metal | Chemical formula of the base | Metal |
|------|-------------------------------|-----------|------------------------------|-------|
| 1. | H₃PO₄ | | Na₂O | |
| 2. | | Carbon | | Potassium |
| 3. | H₂SO₄ | | NH₄OH | |
| 4. | HCl | | | Magnesium |
| 5. | | Nitrogen | Fe₂O₅ | |

So we are to fill in the blanks.

Let’s complete it:

#### Row 1:
- Acid: H₃PO₄ → from P (phosphorus) → Non-metal: Phosphorus
- Base: Na₂O → from Na (sodium) → Metal: Sodium

✔ So:
- Non-metal: Phosphorus
- Metal: Sodium

#### Row 2:
- Non-metal: Carbon
- Metal: Potassium
- So acid from carbon → H₂CO₃
- Base from potassium → KOH

✔ So:
- Acid: H₂CO₃
- Base: KOH

#### Row 3:
- Acid: H₂SO₄ → from Sulfur → Non-metal: Sulfur
- Base: NH₄OH → from Nitrogen → Non-metal: Nitrogen
- No metal involved → Metal: — (leave blank)

✔ So:
- Non-metal: Sulfur
- Metal: —

#### Row 4:
- Acid: HCl → from Chlorine → Non-metal: Chlorine
- Metal: Magnesium
- So base: Mg(OH)₂

✔ So:
- Non-metal: Chlorine
- Base: Mg(OH)₂

#### Row 5:
- Non-metal: Nitrogen
- Base: Fe₂O₅ → likely a typo. Iron forms Fe₂O₃ (rust), not Fe₂O₅.
- Fe₂O₃ → from Iron (Fe) → Metal: Iron
- Acid from nitrogen: HNO₃

✔ So:
- Acid: HNO₃
- Metal: Iron

But Fe₂O₅ is not a real compound. Probably meant to be Fe₂O₃.

So assuming typo, we proceed.

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Final Completed Table:

| S.No | Chemical formula of the acid | Non-metal | Chemical formula of the base | Metal |
|------|-------------------------------|-----------|------------------------------|-------|
| 1. | H₃PO₄ | Phosphorus | Na₂O | Sodium |
| 2. | H₂CO₃ | Carbon | KOH | Potassium |
| 3. | H₂SO₄ | Sulfur | NH₄OH | — |
| 4. | HCl | Chlorine | Mg(OH)₂ | Magnesium |
| 5. | HNO₃ | Nitrogen | Fe₂O₃ (corrected) | Iron |

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Q-5: Fill in the blanks

a) The metal which is the best conductor of heat and electricity is _________.

✔ Answer: Silver

Silver is the best conductor of heat and electricity among all metals.

b) Out of tin, lead, copper and mercury, the metals that lie above hydrogen in the activity series are ________ and ________.

Let’s recall the activity series:

- Metals above hydrogen displace hydrogen from acids.
- Order (partial):
K > Na > Ca > Mg > Al > Zn > Fe > Pb > H > Cu > Ag > Au

So:
- Tin (Sn) → below H → does not displace H
- Lead (Pb) → just below H → does not displace H
- Copper (Cu) → below H
- Mercury (Hg) → below H

Wait — all four are below hydrogen?

But tin (Sn) and lead (Pb) are slightly above hydrogen in some versions?

Actually, standard activity series:

- Tin (Sn) → below H
- Lead (Pb) → below H
- Copper (Cu) → below
- Mercury (Hg) → below

But some sources place tin and lead just above hydrogen.

Wait — check:

- Zinc (Zn) → above H
- Iron (Fe) → above H
- Lead (Pb) → just below H — does not displace H from dilute acids
- Tin (Sn) → also below H
- Copper (Cu) → below
- Mercury (Hg) → below

So none of these four are above hydrogen?

But the question says “the metals that lie above hydrogen” — implying at least one.

Wait — tin (Sn) and lead (Pb) do react with hot concentrated acids but not with dilute acids.

In standard activity series, hydrogen is placed between Pb and Cu.

So:
- Pb → above H
- Sn → above H
- Cu → below
- Hg → below

Yes! Actually, tin and lead are above hydrogen in the activity series.

For example:
- Tin reacts with HCl (slowly):
$$
Sn + 2HCl \rightarrow SnCl₂ + H₂
$$
- Lead reacts with H₂SO₄ but not with HCl due to coating.

So, both tin and lead are above hydrogen.

✔ So the metals that lie above hydrogen are: Tin and Lead

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✔ Final Answers:

#### Q-1: c) produces stillness when dropped
#### Q-2: a) Iron is a metal and it reacts with water vigorously
#### Q-3: d) P (Phosphorus)
#### Q-4: Filled table as above
#### Q-5:
a) Silver
b) Tin and Lead

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Let me know if you want the completed table formatted clearly!