Chemistry Flashcards
7 cards from real GCSE practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Chemistry flashcards as text
Which of the following substances is a mixture rather than a pure compound?
Answer: Air
Air is a mixture of nitrogen, oxygen, argon, and other gases that are not chemically combined.
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 share the same number of outer shell (valence) electrons, giving them similar chemical properties.
What type of reaction occurs when iron rusts in the presence of water and oxygen?
Answer: Oxidation
Rusting is an oxidation reaction in which iron loses electrons and combines with oxygen to form iron(III) oxide.
Which separation technique would best separate a mixture of salt and sand?
Answer: Dissolving in water, filtering, then evaporating
Salt dissolves in water while sand does not; filtering removes the sand, and evaporation recovers the salt.
What is the pH of a neutral solution at 25°C?
Answer: 7
A neutral solution has equal concentrations of H⁺ and OH⁻ ions, giving a pH of exactly 7 at 25°C.
Which of the following correctly describes an isotope?
Answer: Atoms of the same element with different numbers of neutrons
Isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons.
When magnesium burns in oxygen, the product formed is:
Answer: Magnesium oxide
Magnesium reacts vigorously with oxygen to form magnesium oxide (MgO), a white solid.