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Combined Science
Key terms
Parts per million (ppm)

GCSE Combined Science · key term

Parts per million (ppm)

Definition

A unit of concentration. For atmospheric gases, 316 ppm means 316 molecules of that gas per million molecules of air.

Used by OCR

How each exam board covers it

OCR GCSE Combined Science B · J260

Chemistry, Combined Science

Parts per million, or ppm, expresses this concentration: 316 ppm means 316 carbon dioxide molecules per million molecules of air.
Revise: Greenhouse Effect and Evidence for Climate Change

OCR Combined Science B past papers

Related key terms

Anthropogenic
Climate change
Correlation
Fossil fuel
Greenhouse effect

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Parts per million (ppm) — OCR GCSE Combined Science B Definition

Infrared radiation

Order of magnitude