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

II and IV.

Explanation:

I. (INCORRECT). A model is a tentative to determinate a thing that can't be proved, and it's made based on evidence. If the model can explain the observation in nature, it is considered right, although it can be proved by a theory.

II. (CORRECT). The most accepted model of atoms says that they're formed by tiny particles, protons, neutrons, and electrons, with the first two on the nucleus, and the other surrounding it in an open space.

III. (INCORRECT). A heterogeneous mixture is a mixture of substances that is possible to identify phases of them, such as in oil and water. In the air, isn't possible to identify the constituents, and it's a homogeneous mixture.

IV. (CORRECT). Silver has atomic number 47, which is its number of protons. The atomic mass is the sum of protons and neutrons, so the number of neutrons is 108 - 47 = 61.

all eukaryotic cell have mitochondria : )