Answer briefly.
Can you store pickle in an aluminium utensil? Give reason.
No, you cannot store pickle in an aluminium utensil because pickles are acidic and can react with aluminium, leading to corrosion and the formation of harmful substances.
Tabulate the differences between metals and non-metals.
| Property | Metals | Non-Metals |
|---|---|---|
| Physical State | Solid (except mercury) | Solid, liquid, or gas |
| Appearance | Shiny (metallic lustre) | Dull (except diamond) |
| Hardness | Generally hard (except sodium, potassium) | Generally soft (except diamond) |
| Malleability | Malleable | Non-malleable |
| Ductility | Ductile | Non-ductile |
| Conductivity | Good conductors of heat and electricity | Poor conductors (except graphite) |
| Melting/Boiling Points | High | Low |
| Sonorousness | Sonorous | Non-sonorous |
Why are utensils made up of aluminium and brass?
Aluminium is used because it is lightweight, has good thermal conductivity, and is resistant to corrosion. Brass is used for its durability, attractive appearance, and resistance to corrosion.
Define Alchemy.
Alchemy is an ancient practice that aimed to transform base metals into noble metals like gold, discover a universal cure for diseases, and achieve eternal life.
Name the elements with the following symbols.
a) Na b) W c) Ba d) Al e) U
- a) Na: Sodium
- b) W: Tungsten
- c) Ba: Barium
- d) Al: Aluminium
- e) U: Uranium
Name six common non-metals and write their symbols.
Oxygen (O), Nitrogen (N), Carbon (C), Sulphur (S), Phosphorus (P), Chlorine (Cl)
Mention any four compounds and their uses.
a) Water (Hâ‚‚O): Used for drinking, cleaning, and as a solvent.
b) Sodium chloride (NaCl): Used as table salt in food.
c) Carbon dioxide (COâ‚‚): Used in carbonated beverages and fire extinguishers.
d) Ammonia (NH₃): Used in cleaning products and fertilizers.
Name the metals that are used in jewellery.
Gold (Au), Silver (Ag), Platinum (Pt), and sometimes Palladium (Pd).
Mention the uses of the following compounds.
a) Baking soda b) Bleaching powder c) Quick lime
a) Baking soda (NaHCO₃): Used in baking as a leavening agent, in cleaning, and as an antacid.
b) Bleaching powder (CaOClâ‚‚): Used for bleaching fabrics, disinfecting water, and sanitizing surfaces.
c) Quick lime (CaO): Used in construction (cement and mortar), in the steel industry, and for soil stabilization.
Give reasons for the following.
(a) Aluminium foils are used to wrap food items.
Aluminium foils are used to wrap food items because aluminium is non-toxic, lightweight, and a good conductor of heat. It provides a barrier to light, oxygen, moisture, and bacteria, which helps to keep food fresh and prevent spoilage.
(b) Immersion rods for heating liquids are made up of metallic substances.
Immersion rods for heating liquids are made up of metallic substances because metals are good conductors of heat and electricity. They can efficiently transfer heat to the liquid, making the heating process quick and effective.
(c) Sodium and potassium are stored in kerosene.
Sodium and potassium are stored in kerosene because they are highly reactive metals, especially with water and moisture in the air. Storing them in kerosene prevents their contact with air and moisture, thus preventing potentially dangerous reactions.
(d) Mercury is used in thermometers.
Mercury is used in thermometers because it has a high coefficient of expansion and a uniform rate of expansion over a wide range of temperatures. It is also a good conductor of heat and remains in liquid form at a wide range of temperatures, making it ideal for accurately measuring temperature.
Why wires cannot be drawn from materials such as stone or wood?
Wires cannot be drawn from materials such as stone or wood because these materials lack ductility. Ductility is the property that allows materials to be stretched into thin wires without breaking. Stone and wood are brittle and lack the ability to deform plastically, making them unsuitable for being drawn into wires.
