K12 chemistry unit assessment: chemical bonding,

electrostatic forces in ionic bonds hold which of the following together? 1. He atoms in helium gas 2. Na + and Br - in NaBr 3. Fe atoms and localized electrons in iron

Is one mole of zinc the same as one atom of zinc?

Among atoms with low atomic numbers what is the neutron-proton ratio of the most stable nuclei

List two solutions you can drink

List four ways the rate at which a particular solute dissolves can be increased

Could you separate a mixture of salicylic acid and aspirin by acid-base extraction? briefly justify your answer.

The air in an inflated balloon (the system) absorbs 125 J of heat from its proximity to a fire. The balloon expands and does 85 kJ of work. What is the change in internal energy (in kJ) (ΔU) for the system? Round to the nearest whole number.

Is a cytoplasm made of 80 percent of water

Calculate the acid concentration of a sample of acid rain with a ph of 4.20

1. Examine Record A. Use the three basic rules to figure out the ages of the layers. In Chart A, list the layers from youngest to oldest with the youngest layer in the first row.

What are three reasons why a population might change?