Elements Compounds and Mixtures
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Elements Compounds and Mixtures — Free MYP3 Sciences Practice Questions

1QuestionCompounds and Chemical FormulaeConcept Practice
2 marks~3 minCriterion A
The chemical formula for water is H2O\text{H}_2\text{O}.
a
State the name of the element represented by the symbol O in the formula H2O\text{H}_2\text{O}. [1]
b
Explain why H2O\text{H}_2\text{O} is classified as a compound rather than a mixture. [1]
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Solutions

2QuestionDefinition of Elements and SymbolsAssessment Practice
3 marks~5 minCriterion B
The graph below shows the first ionisation energy (in kJ/mol) for elements with atomic numbers 11 to 18 (sodium to argon).
a
State the general trend in first ionisation energy from sodium to argon. [1]
b
Explain this trend using atomic structure. [2]
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Solutions

3QuestionCompounds and Chemical FormulaeAssessment Practice
4 marks~6 minCriterion D
A student reads two snack ingredient lists. One states "contains sodium chloride (NaClNaCl)" and the other states "contains salt."
a
Describe what NaClNaCl represents and identify the common name for this compound. [1]
b
Explain why using NaClNaCl instead of "salt" on a food label could confuse consumers. [1]
c
A food company must choose whether to list ingredients using chemical formulas or common names. Analyse one advantage and one disadvantage of requiring chemical formulas on all food labels. [2]
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Solutions

4QuestionIdentifying Substances from Their PropertiesAssessment Practice
4 marks~6 minCriterion C
A student tests three white powders — X, Y, and Z — by heating each one and recording its melting point.

Melting point of X: 801°C801°C
Melting point of Y: 186°C186°C
Melting point of Z: 100°C100°C

Known melting points — sodium chloride: 801°C801°C; sucrose: 186°C186°C; wax: ≈100°C\approx 100°C
a
State which powder is sodium chloride. [1]
b
Explain why melting point can be used to identify a pure substance. [1]
c
A fourth powder, W, melts at 184°C184°C. Analyse whether powder W is the same substance as powder Y. Support your answer with evidence from the data. [2]
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Solutions

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