To understand the world we live in, we use mental models. What is the problem with mental models? (Select all that apply)

•They are personal

•They are incomplete

•They are idiosyncratic

•They are untestable

For each event stated, indicate how the concentration of each species in the chemical equation will change to re-establish equilibrium.

All oxygen atoms have eight protons, and most have eight neutrons as well. What is the mass number of an oxygen isotope that has nine neutrons? What is the name of this isotope?

After 4 half-lives have elapsed, the amount of a radioactive sample which has not decayed is

An element A has a triiodide with the formula AI₃ and a trichloride with the formula ACl₃. The triiodide is quantitatively converted to the trichloride when it is heated in a stream of chlorine, according to the reaction.

What are structure for each of the compounds listed. Explain why the name given is incorrect. And give a correct name in each case (1) 1-methylbutane (2) 1,1,3-trimethylhexane (3) 5octyne (4) 2-ethyl-1-propanol (5) 2,2-dimethyl1-3-butanol

If the half-life of hydrogen-3 is 11.8 years, after two half-lives the radioactivity of a sample will be reduced to one-half of the original amount. If the half-life of hydrogen-3 is 11.

If element X has 25 protons, how many electrons does it have?

How much work is done to raise a 20N box 4m?

Which of the following lists the types of single substances? (Select only one answer) Group of answer choices elements and mixtures suspensions, solutions, and colloids elements, compounds, and mixtures elements and compounds

What is the average mass of a single silicon atom in grams?