HELP WILL AWARD BRAINLIST! While sorting through a pile of old Petri dishes, Alexander Fleming noticed that the mold in one of the dishes prevented bacteria from growing there. He decided to study the mold. Years later, other scientists used the active compound in this mold to develop the first antibiotic, penicillin. Which statement describes Alexander Fleming's scientific discovery?

He made a discovery that disproved all other theories.

He made a discovery by working with a group of scientists.

He made a discovery by carefully following and repeating a procedure.

He made a discovery without using all the steps of the scientific method.

The identities of substances are the same before and after which type of change

In an experiment, 45g of silicon tetrachloride are treated with 45ml of water. what is the theoretical yield in grams of hcl

1.) which of the following is a molecule but not a compound? a.he b.f2 c.h2o d.ch4 2.) what is a physical combination of substances? a.a compound b.a molecule c.a mixture d.an element 3.) what is a chemical combination of substances? a.a compound b.an atom c.a mixture d.an element 4.) what is the relationship between the solute and solvent in a solution? a.they form a compound b.they form a mixture c.they form molecules d.they form chemical bonds 5.) the gases in air dissolve in water. what would be one way to reduce the amount of a gas dissolved in water? a.add more water b.reduce the air pressure c.increase the air pressure d.stir the water 6.) how would you determine the solubility of a substance? a.find how well it dissolved various substances. b.find the mass and the volume of the substance. c.find the temperature at which the substance evaporated. d.find how much i was able to dissolve in a solute. 7.) the periodic table organizes all of the kinds of a.molecules. b.compounds. c.atoms. d.ions. 8.)what distinguishes two substances combined to become a compound vs. two substances combined to become a mixture? a.whether they can be easily separated b.whether they chemically bond together c.whether they both are visible d.whether they are heterogeneous 9.) the principle components of air are: n2 78% o2 21% ar 0.95% co2 0.038% this is a solution of a.molecules and atoms. b.molecules. c.compounds and molecules. d.atoms.