Determine the number of protons neutrons and electrons in an isotope that has 21 neutrons and a mass number of 40

Magnesium would acquire a stable arrangement of electrons by bonding with one atom of which of the following elements? oxygen chlorine helium nitrogen

The part that includes land and water

What is the mass of 5.0 cm^3 piece of copper having a density of 8.96 g/cm^3

Hydrogen has three isotopes 1H, 2H, and 3H. What is the difference between these three isotopes?

Which labels best complete the diagram? X: High resistance Y: Low resistance Z: Flow of electrons X: Low resistance Y: Flow of electrons Z: High resistance X: Flow of electrons Y: High potential energy Z: Low potential energy X: Low potential energy

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.