Question

a) An isotope with 20 protons or less will be stable if: select all that apply

it has more protons than neutrons, it has more protons than electrons, it has more electrons than protons, it has more electrons than neutrons, it has same # of protons and neutrons, it has same # of protons and electrons

b) an isotope with more than 83 protons is: select all that apply

stable, unstable or radioactive, will be stable or unstable depending on proton to neutron ratio, will be stable or unstable depending on its electron to neutron ratio, will be unstable or stable depending on its proton to electron ratio

Answer 1

Isotopes are elements which have same number of protons and electrons but different number of neutrons. Thus the isotope of an elements will weigh comparatively higher than the original element.

Eg. Hydrogen has two isotopes: Deutrium and Tritium. Both will have higher mass than Hydrogen as Deutrium has 1 neutron more than Hydrogen and Tritium has 2 neutron more than Hydrogen.

a) In the first question a stable neutron will be produced if there are same number of protons and neutrons. Also in isotopes there are same number of protons and electrons. Thus last two options are applicale for an isotope for less than 20 protons.

b) All the isotope above atomic number 83 are RADIOACTIVE AND UNSTABLE. They will decay according to the half life. They are radioactive because they do not have proper combination of proton to neutron ratio.