General Science • Topic 4 of 4

Science in Everyday Life

Everyday science links principles to daily observations: lightning is seen before thunder because light is faster than sound; a pressure cooker cooks faster because higher pressure raises water's boiling point.

Why everyday things happen

ObservationReason
Lightning seen before thunder heardlight travels much faster than sound
Pressure cooker cooks fasterhigher pressure raises water's boiling point
Swimming pool looks shallower than it isrefraction (bending) of light
Iron rustsreaction with oxygen + moisture
We get Vitamin D from the morning sunskin makes it from sunlight
Mixture vs compound. A mixture (e.g., salt in water) can be separated by physical methods like filtration or distillation; a compound (e.g., water itself) cannot — it needs a chemical reaction. LPG cooking gas is mainly butane and propane.

✅ Solved examples

1. Why is lightning seen before thunder is heard?
Light travels much faster than sound.
2. Why does a pressure cooker cook food faster?
Higher pressure raises water's boiling point.
3. Which vitamin is made by the skin in sunlight?
Vitamin D.
4. LPG mainly consists of which gases?
Butane and propane.

✏️ Practice — try these, take hints as needed

1. We hear thunder after lightning because light is ___ than sound.
Speed.
—
—
Faster
2. A pressure cooker raises the ___ point of water.
Where it boils.
—
—
Boiling point
3. Sunlight helps the body make Vitamin ___.
Letter.
—
—
D
4. Filtration can separate a ___ (not a compound).
Physical combo.
—
—
Mixture
5. Cooking gas (LPG) is mainly butane and ___.
Propane.
—
—
Propane

📝 Topic test — 8 questions

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