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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.

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  1. What type of isomerism do butane and methylpropane exhibit?

    Answer: Structural isomerism

    Butane (CH₃CH₂CH₂CH₃) and methylpropane ((CH₃)₂CHCH₃) are structural isomers — same molecular formula (C₄H₁₀), different arrangements.

  2. Which type of chemical bond is formed when electrons are transferred from one atom to another?

    Answer: Ionic bond

    Ionic bonds are formed by the transfer of electrons from a metal atom to a non-metal atom, creating oppositely charged ions.

  3. What is the test for carbon dioxide gas?

    Answer: Turns limewater milky

    Carbon dioxide turns limewater (calcium hydroxide solution) milky/cloudy due to the formation of calcium carbonate precipitate.

  4. In the periodic table, elements in the same group have the same number of:

    Answer: Electrons in the outer shell

    Elements in the same group have the same number of electrons in their outermost shell, giving them similar chemical properties.

  5. What is produced when ethanol reacts with ethanoic acid?

    Answer: Ethyl ethanoate and water

    Esterification: ethanol + ethanoic acid → ethyl ethanoate (an ester) + water, in the presence of a concentrated acid catalyst.

  6. What is the term for the minimum energy required for a reaction to occur?

    Answer: Activation energy

    Activation energy is the minimum energy that colliding particles must possess for a reaction to occur and form products.

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