Which of the following statements are true? i. models are always wrong unless they are proved by a theory. ii. elements, such as lead, are made of tiny particles that mostly consist of open space. iii. the air you breathe is an example of a heterogeneous mixture. iv. an isotope of silver-108 has 61 neutrons.

I. Models are always wrong unless they are proved by a theory. TRUE

II. Elements, such as lead, are made of tiny particles that mostly consist of open space. FALSE

III. The air you breathe is an example of a heterogeneous mixture. FALSE

IV. An isotope of silver-108 has 61 neutrons. TRUE

Explanation:

I. All models are wrong because in order for them to be applied to reality, certain aspects that do not fit the theory must be considered.

II. All elements are made by atoms.

III. The air is an example of a homogeneous mixture of different gases. IA homogeneous system is that material system that has the same intensive properties in any part of that system. One way to check it is by viewing it. If the different parts that make it up cannot be distinguished, it will be homogeneous.

IV. Atomic number of Silver is 47. So if its mass number is 108, it has 61 neutrons and 47 protons

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