7. Which one is the best way to determine whether an unknown sample substance or a mixture? A. Knowing its density B. Tasting the given sample c. Observing its physical appearance D. Testing its melting and boiling point
8. Which is NOT a technique to separate components of mixture? A. Condensation C. Evaporation B. Distillation D. Filtrati
9. Which of the following is a heterogeneous mixture? A Air C. Stainless steel B. Oil in water D. Soft drink
10. What is/are true for substance and mixture? 1. Pure substance melts completely. II. Pure substance has a varying boiling point. III. Mixture does not melt completely. IV. Mixture has a fixed boiling point. C. II and IV only B. I and III only A. I and II only D. I and IV only

Can you please help me this problem? ​