The atom is krypton and its symbol is Kr.
the mass number is 41 + 36 = 77
its charge is 0 as it is a noble gas.
The substances Oxygen and Hydrogen are elements.
As we go down the group the number of energy level increases
and the nuclear attraction decreases
therefore ability to remove electron increases
therefore first ionization energy decrease(as it can be removed easily the energy needed is less)
Therefore answer c
Answer:
6.022x10^23 molecules
Explanation:
Since it's one mole of CaCO3, multiply by Avogadro's number to get molecules
Answer: An element with the same number of protons, but a different number of neutrons
Explanation:
The # of protons in an atom is what determines what atom it is (hydrogen has 1 proton, helium has 2 protons, etc ...). You cannot change the number of protons in an atom without changing what element the atom is.
The number of electrons in atoms varies greatly because electrons are constantly gained, lost, and shared during chemical reactions.
An isotope is a variation of the same element (so they must have the same # of protons) that have different masses (and therefore a different number of neutrons).
The answer is the fourth choice, "An element with the same number of protons, but a different number of neutrons"