Potassium has a mass number of 40 and an atomic number of 19. how many protons does it have?

When many students measure the concentration of the same solution for a chemistry course laboratory assignment, do their measurements follow a normal distribution?

Non-metal liquid with 45 neutrons

What is the theoretical yield of sodium oxide (Na₂O) in grams when 20.0g of calcium oxide (CaO) reacts with an excess amount of Sodium chloride? 2NaCl+CaO->CaCl2+Na2O The 2 at the end of the equation is not a coefficient it's for Na2. 10.0g 22.1g 32.

What option gives the correct mole ratio

For a single H2 molecule, H2 → 2H, the dissociation energy is 4.52 eV. How much energy would have to be put in (in kJ) to dissociate a mole of hydrogen molecules?

Assuming that air contains 78 percent N2, 21 percent O2 and 1 percent Ar, all by volume. How many molecules of each type of gas are present in 1.0 L of air at STP?

Two children are playing tag. Child A who is doing the chasing can run 100m in 24 seconds Child B is running away from child A and can run 64m in 21 seconds.

What ion does a base increase

What is the definition of Amplitude?

An excess of NiCO3, 12 g, was added to 40cm cube of sulpheric acid, 2.0 mol/dm cube. The unreacted nickel carbonate was filtered out and the filtrate evaporated to optain the crystals.