Determine the number of neutrons for the given isotopes. helium-3 carbon-14 nitrogen-15 strontium-90 tellurium-123

I know this is a very broad question but can someone explain ions, I am so confused.

Which tide occurs during a full or new Moon and is characterized by an extra-high tide caused by the straight-line arrangement of the Sun, Moon, and Earth? A. low B. neap C. spring

Nickel has an atomic mass of 58.69, and cobalt has an atomic mass of 58.93. Despite this, Mendeleev listed cobalt before nickel in his periodic table. What information caused Mendeleev to order the elements in this way?

Never trust Wikipedia .

How does refraction work? A. Light speeds up as it goes through more dense materials. B. Light waves bend when they go through a small slit or hole. C. Light slows down as it goes through more dense materials. D.

How do you know if an element is an ion?

Which gas is not a greenhouse gas, A methane, B Water Vapor, C, Carbon dioxide, D, Nitrogen, E, Ozone

A very small equilibrium constant means ... a. an equal amount of reactants and products c. more products b. more reactants d. system isn't at equilibrium

What is in a banana? give me specifics?!

When 17.28 mL of a 0.078 M aqueous solution of Na2SO4 is combined with 11.30 mL of a 0.20 M aqueous solution of NaCl and 7.84 mL of a 0.26 M aqueous solution of KCl, what is the total concentration of Na + in the combined solution?