This document contains 30 exam questions about mixtures and pure substances that cover key topics such as: - Defining mixtures and pure substances and providing examples of each. - Explaining the differences between mixtures and pure substances in terms of separation processes and component amounts. - Describing heterogeneous and homogeneous mixtures, solutions, physical and chemical changes, and solution component types. - Identifying separation techniques for mixtures such as decanting, filtration, magnetic attraction, sifting, precipitation, crystallization, and distillation. - Comparing elements and compounds as well as properties of pure substances like melting point, boiling point, and density. - Discussing primordial elements in the universe and specific elements like hydrogen and

1. EXAM QUESTIONS (to learn better) for Lesson 4 Mixtures and pure substances.
1º.- What is a mixture?. Give some examples.
2º.- What is a pure substance?. Give some examples.
3º.- Explain the difference between mixtures and pure substances.
4º.- Explain the difference between mixtures and pure substances according to the separation processes.
5º.- Explain the difference between mixtures and pure substances according to the amount of their
components.
6º.- Explain the difference between heterogeneous and homogeneous mixtures.
7º.- What is a solution?. Give some examples.
8º.- What are physical changes?.
9º.- What are chemical changes?.
10º.- Explain the components in a solution.
11º.- Explain the types of solution according to the amount of its components.
12º.- What is a diffusion?. Give some examples.
13º.- What is a alloy?. Give some examples.
14º.- Which are the separation techniques for mixtures?.
15º.- Explain decanting. When is this technique used?.
16º.- Explain filtration. When is this technique used?.
17º.- Explain magnetic attraction. When is this technique used?.
18º.- Explain sifting. When is this technique used?.
19º.- Explain precipitation. When is this technique used?.
20º.- Explain crystallisation. When is this technique used?.
21º.- Explain distillation. When is this technique used?.
22º.- Explain how pure substances are differentiated. Give some examples.
23º.- Explain the difference between an element and a compound.
24º.- Explain the melting point for the pure substances.
25º.- Explain the boiling point for the pure substances.
26º.- Explain the density for the pure substances.
27º.- Explain the primordial elements making up the universe.
28º.- Explain hydrogen and its main uses.
29º.- Explain helium and its main uses.
30º.- Explain nuclear fusion and fission.