I. Choose the Best Answer (MCQs)
Q1. Matter is composed of
- (a) Atoms (b) Molecules (c) Ions (d) All of the above
Q2. The liquid metal used in thermometers is
- (a) Copper (b) Mercury (c) Silver (d) Gold
Q3. Which element name is not derived from a planet?
- (a) Plutonium (b) Neptunium (c) Uranium (d) Mercury
Q4. Symbol of Mercury is
- (a) Ag (b) Hg (c) Au (d) Pb
Q5. A form of non-metal which has high ductility is
- (a) Nitrogen (b) Oxygen (c) Chlorine (d) Carbon
Q6. Which metal possesses low tensile strength?
- (a) Silver (b) Copper (c) Zinc (d) Aluminium
Q7. The property which allows metals to be hammered into sheets is
- (a) Ductility (b) Malleability (c) Conductivity (d) Tensile strength
Q8. The non-metal which conducts current is
- (a) Carbon (b) Oxygen (c) Aluminium (d) Sulphur
Q9. Pencil lead contains
- (a) Graphite (b) Diamond (c) Aluminium (d) Sulphur
Q10. (Additional) Most reactive metal is
- (a) Iron (b) Copper (c) Sodium (d) Potassium
II. Fill in the Blanks
1. The elements possessing character of both metals and non-metals are called metalloids. 2. The symbol of Tungsten is W (from its German name Wolfram). 3. Melting point of most metals is higher than non-metals. 4. Water contains hydrogen and oxygen elements. 5. Silicon/Germanium is used in the semiconductor industry. 6. The atom or group of atoms having a charge is called ions. 7. Each element is denoted by a symbol. 8. Metals and non-metals are used for making tools, machines, cars. 9. Osmium is so hard it can scratch glass. 10. The typical shine of metals is called metallic lustre.
III. True or False
IV. Match the Following
Match 1 — Substances and Uses:
| A | B | Answer |
|---|---|---|
| Iron | For making wires | Sewing needle |
| Copper | Sewing needle | For making wires |
| Tungsten | As a fuel for ignition in rocket | Making filament of a bulb |
| Boron | Making filament of a bulb | As a fuel for ignition in rocket |
Match 2 — Terms and Definitions:
| Term | Definition | Answer |
|---|---|---|
| Atom | Building block of matter | A |
| Element | Atoms of the same kind | C |
| Compound | Atoms of different kinds | B |
| Molecule | Smallest unit of a substance | D |
Match 3 — State of Matter (image-based): A — gas, B — solid, C — liquid
V. Very Short Answers
Q1. What is ductility? Answer: The property that allows metals to be drawn into thin wires. Example: Copper is drawn into electrical wires.
Q2. Write constituent elements and symbols for: (a) Carbon monoxide (b) Washing soda Answer: (a) Carbon monoxide — Symbol: CO; Elements: Carbon and Oxygen (b) Washing soda — Symbol: Na2CO3; Elements: Sodium, Carbon, and Oxygen
Q3. Write symbols for: Oxygen, Gold, Calcium, Cadmium, Iron Answer: O, Au, Ca, Cd, Fe
Q4. Name two soft metals that can be cut with a knife. Answer: Sodium (Na) and Potassium (K) are soft enough to be cut with a knife.
Q5. Which non-metal is essential for life and inhaled during breathing? Answer: Oxygen — essential for all living beings and inhaled during respiration.
Q6. Why are bells made of metals? Answer: Metals are sonorous — they produce a ringing sound when struck, making them ideal for bells.
Q7. What does a chemical symbol represent? Answer: A chemical symbol is a shorthand representation of an element. It signifies: (1) the name of the element, and (2) one atom of that element. Example: O represents oxygen and one atom of oxygen.
Q8. Give two examples of metalloids. Answer: Boron and silicon.
Q9. Mention three compounds that exist in liquid state. Answer: Water, Hydrochloric acid, and Nitric acid.
Q10. Write three properties of metalloids. Answer: 1. Metalloids are all solid at room temperature. 2. They can form alloys with metals. 3. Some metalloids (like silicon and germanium) act as semiconductors under specific conditions.
VI. Short Answers
Q1. Can you store pickle in an aluminium utensil? Explain. Answer: No. Lemon pickle is acidic, and aluminium is a metal. Acids react with metals to produce hydrogen gas, which would spoil the food and make it unfit for consumption.
Q2. Tabulate four differences between metals and non-metals.
| Property | Metals | Non-metals |
|---|---|---|
| Physical state at room temp | Usually solid | Solid, liquid, or gas |
| Malleability | Good (hammered into sheets) | Poor — usually brittle |
| Ductility | Good (drawn into wires) | Poor — usually brittle |
| Boiling point | Usually high | Usually low |
Q3. Define tensile strength. Answer: The capacity of metals to withstand strain without breaking is called tensile strength. This is why iron is used for railway tracks.
Q4. Why are utensils made of aluminium and brass? Answer: Cooking utensils use aluminium and brass because they are good conductors of heat. Aluminium also forms a protective oxide layer that prevents further reaction, and it is relatively inexpensive.
Q5. Define Alchemy. Answer: Alchemy was a form of chemistry studied in the Middle Ages, concerned with trying to discover ways to change ordinary metals into gold.
Q6. Name elements for these symbols: Na, W, Ba, Al, U Answer: Sodium, Tungsten, Barium, Aluminium, Uranium.
Q7. Name six common non-metals with symbols. Answer: Sulphur (S), Carbon (C), Oxygen (O), Hydrogen (H), Helium (He), Nitrogen (N).
Q8. Mention four compounds and their uses.
| Common Name | Chemical Name | Uses |
|---|---|---|
| Water | Hydrogen oxide | Drinking, solvent |
| Table salt | Sodium chloride | Daily diet, preservative |
| Sugar | Sucrose | Sweets, juices |
| Baking soda | Sodium bicarbonate | Fire extinguisher, baking |
Q9. Which metals are used in jewellery? Answer: Silver and gold are used for making jewellery and decorative purposes.
Q10. Uses of compounds: (i) Baking soda — Fire extinguisher, baking powder, cakes and bread (ii) Bleaching powder — Bleaching agent, disinfectant, sterilising drinking water (iii) Quick lime — Manufacture of cement and glass
VII. Detailed Answers
Q1. Give reasons: 1. Aluminium foils wrap food items — Aluminium is malleable, soft, and does not react with food items. 2. Immersion rods are metallic — Metals are good conductors of heat and electricity. 3. Iron deficiency tablets don't look like iron — Iron tablets contain iron salts (ferrous sulphate, ferrous citrate), not iron metal. 4. Sodium and potassium stored in kerosene — They are very reactive with air and water; kerosene prevents reactions. 5. Mercury used in thermometers — Mercury has high density and expands uniformly at different temperatures.
Q2. Why can't wires be drawn from stone or wood? Answer: Stone and wood are non-conductors of electricity and lack ductility (the property to be drawn into wires), so they cannot be drawn into wires.
Additional Questions
Physical Properties of Non-metals
1. Physical state: Can be solid (sulphur), liquid (bromine), or gas (oxygen). 2. Hardness: Generally not hard except diamond. 3. Lustre: Dull appearance; graphite and iodine are exceptions. 4. Density: Generally low; diamond is the hardest natural substance (exception). 5. Melting/boiling point: Low; carbon, silicon, and boron are exceptions. 6. Tensile strength: Generally lack tensile strength; carbon fibre is an exception. 7. Malleability: Non-malleable; solid non-metals are brittle. 8. Ductility: Generally not ductile; carbon fibre is an exception. 9. Conductivity: Bad conductors; graphite is an exception. 10. Sonorous: Non-metals do not produce sound when hit.
Uses of Metals
- Iron — bridges, engine parts, iron sheets and bars
- Copper — electrical wires, coins, statues
- Silver and Gold — jewellery, decorative purposes, photography
- Mercury — thermometers and barometers
- Aluminium — electrical wires, cables, aerospace industries
- Lead — automobile batteries, X-ray machines
Uses of Non-metals
- Diamond — jewellery, cutting and grinding equipment
- Graphite — pencil lead
- Sulphur — gunpowder, vulcanization of rubber
- Phosphorus — matches, rat poison
- Nitrogen — manufacturing ammonia
- Chlorine — bleaching agent, sterilizing water
- Hydrogen — rocket fuel, cutting and welding
Common Mistakes
- Saying gases have fixed volume: Gases have neither fixed shape nor fixed volume.
- Confusing malleability with ductility: Malleability is hammering into sheets; ductility is drawing into wires.
- Treating all non-metals as non-conductors: Graphite (carbon) conducts electricity — it is an exception.
- Confusing symbol conventions: Hg is mercury (not hydrogen-gold), W is tungsten (from Wolfram), Fe is iron (from Ferrum).
- Saying mercury is a gas at room temperature: Mercury is the only metal that is liquid at room temperature.
- Forgetting exceptions in non-metals: Diamond (hardest), graphite (conductor), carbon fibre (ductile) are important exceptions.
Exam Checklist
- [ ] Can you distinguish between metals and non-metals with at least 4 properties?
- [ ] Can you define and give examples of malleability and ductility?
- [ ] Can you explain what metalloids are and name examples?
- [ ] Can you state why sodium and potassium are stored in kerosene?
- [ ] Can you list uses of common metals (iron, copper, aluminium, mercury)?
- [ ] Can you list uses of common non-metals (carbon, sulphur, nitrogen, chlorine)?
- [ ] Can you explain why pickle should not be stored in aluminium utensils?
- [ ] Can you identify chemical symbols for common elements?
- [ ] Can you describe the difference between atoms, molecules, and compounds?
- [ ] Can you name exceptions among non-metals (diamond, graphite)?