Classification of Mixtures and Purity Determination

Try these questions

5 questions from this lesson’s quiz. Start the lesson to answer them and see the right answers.

1. 1. Which of the following is a homogeneous mixture?

   • A. Muddy river water
   • B. Cooking oil and water
   • C. Clean air
   • D. Githeri (maize and beans)

2. 2. Salt is dissolved in pure water. How does the salt affect the boiling point and melting point of the water?

   • A. Boiling point is raised and melting point is lowered
   • B. Boiling point is lowered and melting point is raised
   • C. Both are raised
   • D. Neither changes

3. 3. A pupil heats a clear liquid and the thermometer reading rises steadily from 101 °C to 105 °C while it boils. What can the pupil conclude?

   • A. The liquid is pure water
   • B. The liquid contains dissolved impurities
   • C. The liquid is a gas mixture
   • D. The thermometer is faulty because boiling is always constant

4. 4. Pure water boils at 100 °C at sea level. A salt solution begins to boil at 102 °C. By how many degrees Celsius has its boiling point been raised?

   Type your answer (in °C) in the lesson.

5. 5. What name is given to a mixture that has uniform composition throughout, such as sugar fully dissolved in tea?

   Type your answer in the lesson.

More in Introduction to Integrated Science

• ▸Basic Science Skills and SI Units
• ▸Derived SI Quantities
• ▸Laboratory Apparatus Heating and Mass Measurement
• ▸Optical Instruments and Volumetric Glassware
• ▸Physical Separation Techniques for Mixtures
• ▸Community Service Learning Water Purification Project
• ▸Acids, Bases, and Natural Indicators
• ▸Acids, Bases and the pH Scale

See every Grade 7 Integrated Science lesson →