Homogeneous and Heterogeneous Mixtures - UNSOLVED PRACTICE SET

Q7. Define homogeneous and heterogeneous mixtures. Give one example of each from your kitchen.

Q8. Why is it said that "a homogeneous mixture has a single phase, while a heterogeneous mixture has two or more phases"? Explain with an example.

Q9. Your grandmother prepares a traditional Indian drink called 'shikanji' by mixing lemon juice, water, sugar, and salt. Is this a homogeneous or heterogeneous mixture? Explain by observing the mixture with and without stirring.

Q10. A mixture of sand and salt is a heterogeneous mixture, while salt dissolved in water is homogeneous. Explain the difference in terms of particle size and distribution.

Q11. Can a mixture be partially homogeneous and partially heterogeneous? Give an example to support your answer.

Q12. How would you demonstrate to your classmates that a mixture of chalk powder and water is heterogeneous, even if it looks uniform immediately after shaking?

Q13. With the help of a labelled diagram, explain the difference between homogeneous and heterogeneous mixtures. Give three examples of each from everyday life and describe how you would distinguish between them experimentally.

Q14. A science teacher asks students to classify the following mixtures as homogeneous or heterogeneous: (i) Air, (ii) Soil, (iii) Blood, (iv) Steel, (v) Salad, (vi) Seawater. Some students are confused about blood and steel. Help them by explaining the correct classification with proper reasoning for each.

Q15. "The classification of a mixture as homogeneous or heterogeneous depends on the scale of observation." Do you agree? Present a detailed argument with examples showing how the same mixture might appear different under a microscope versus to the naked eye.

Q16. In a classroom activity, a teacher gives four mixtures to four groups:

Group A: 50 g sugar + 150 g water

Group B: 30 g sand + 120 g water

Group C: 20 g salt + 80 g alcohol

Group D: 40 g oil + 100 g water

(a) Classify each mixture as homogeneous or heterogeneous.

(b) For each heterogeneous mixture, identify the visible phases.

(c) Calculate the percentage by mass of the dispersed phase in each heterogeneous mixture.

(d) Suggest one method to convert Group D's mixture into a homogeneous mixture.

Q17. A student prepares two mixtures:

Mixture X: 5 g of copper sulphate crystals in 100 mL of water — crystals dissolve completely

Mixture Y: 5 g of sand in 100 mL of water — sand settles at the bottom

(a) Classify Mixture X and Mixture Y.

(b) After 1 hour, what will you observe in each beaker? Draw a simple sketch of your expected observation.

(c) If the student filters both mixtures, what will be collected as filtrate and residue in each case?

(d) Calculate the mass percentage of the solute in Mixture X.

Q18. In a village fair, a vendor sells 'lassi' (a traditional yogurt drink). He prepares it by blending yogurt, water, sugar, and ice. Sometimes customers complain that the lassi is too watery at the top and too thick at the bottom.

(a) Is the lassi a homogeneous or heterogeneous mixture? Explain.

(b) What should the vendor do to ensure the lassi remains uniform throughout?

(c) If the vendor uses 200 g yogurt, 100 g water, 30 g sugar, and 50 g ice, calculate the total mass of the lassi.

(d) What percentage of the lassi is yogurt by mass?

(e) Why does the lassi sometimes separate into layers if left undisturbed?