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Combined Science — Chemistry Flashcards

6 cards from real O-LEVEL practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 6 Combined Science — Chemistry flashcards as text

  1. What is the chemical formula for water?

    Answer: H₂O

    Water has the chemical formula H₂O — two hydrogen atoms bonded to one oxygen atom.

  2. Which type of bond involves the sharing of electrons?

    Answer: Covalent bond

    Covalent bonds are formed by the sharing of electron pairs between atoms, typically between non-metal atoms.

  3. What is the pH of a neutral solution?

    Answer: 7

    A neutral solution has a pH of 7. Below 7 is acidic; above 7 is alkaline/basic.

  4. Which gas is produced when an acid reacts with a metal carbonate?

    Answer: Carbon dioxide

    Acid + metal carbonate → salt + water + carbon dioxide. The CO₂ produced turns limewater milky.

  5. What is the relative atomic mass of carbon?

    Answer: 12

    The relative atomic mass of carbon is 12 (specifically, the isotope carbon-12 is the standard reference).

  6. Which type of reaction releases heat energy to the surroundings?

    Answer: Exothermic

    Exothermic reactions release heat energy to the surroundings, causing the temperature of the surroundings to rise.

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