Question 13 (mandatory) (3 points)
ions are atoms of the same element that have a different number of

question 13 options:

nuclei

electrons

neutrons

protons

nucleons

question 14 (mandatory) (3 points)
radium-226 is unstable. what is the process that allows the nucleus of radium-226 to become more stable?

question 14 options:

hydrogen bonding

radioactive decay

nuclear fusion

ionic bonding

covalent bonding

question 15 (mandatory) (3 points)
what parts of an atom can change during a nuclear reaction that cannot change during a chemical reaction?

question 15 options:

the number of electrons only

the number of protons and electrons

the number of neutrons and electrons

the number of protons and neutrons

question 16 (mandatory) (3 points)
traditional explosives use the energy released by chemical reactions. nuclear weapons use the energy released by nuclear reactions. why are nuclear weapons much more destructive than traditional explosives?

question 16 options:

chemical reactions always release more energy than they use

nuclear reactions can release much more energy than chemical reactions

chemical reactions always use more energy than they release

nuclear weapons always contain more chemicals than traditional explosive

chemical reactions can release much more energy than nuclear reactions

question 17 (mandatory) (3 points)
the nucleus of some isotopes will spontaneously undergo nuclear decay. these isotopes are said to be radioactive. what causes the nucleus of an isotope to be radioactive?

question 17 options:

exposure to toxic chemicals

the net charge of the atom

the attraction of protons to electrons

an unstable ratio of protons and neutrons

too many electrons in its orbitals

question 18 (mandatory) (3 points)
if a substance can be separated by physical means and it is not the same throughout, what is it?

question 18 options:

a pure substance

a compound

a heterogeneous mixture

an element

a homogeneous solution

question 19 (mandatory) (3 points)
if a substance cannot be separated by physical means or chemical means, it is

question 19 options:

a mixture

a solution

heterogeneous

a compound

an element

question 20 (mandatory) (3 points)
water vapor turning to frost is an example of .

question 20 options:

deposition

vaporization

sublimation

evaporation

freezing

question 21 (mandatory) (3 points)
what does the atomic number of an element represent?

question 21 options:

the mass of an atom

the number of protons in an atom

the number of neutrons in an atom

the total number of protons, neutrons, and electrons in an atom

the order in which the element was discovered

question 22 (mandatory) (3 points)
which of the following is a common property of noble gases?

question 22 options:

seeks to donate one to three electrons

have a full outer shell of electrons

are highly reactive

easily form chemical compounds

are good conductors of electricity

question 23 (mandatory) (3 points)
which type of element seeks to gain electrons?

question 23 options:

non-metals

noble gases

metals

isotopes

metalloids

question 24 (mandatory) (3 points)
if a material is ductile, it is most likely a .

question 24 options:

non-metal

noble gas

ion

metalloid

metal

question 25 (mandatory) (3 points)
what determines the properties of elements?

question 25 options:

the average atomic mass

the number of electron shells

the number of neutrons

the number of electrons that fill the outer shell

the total number of electrons

question 26 (mandatory) (3 points)
what is happening to the temperature of the substance before and after the phase changes?

question 26 options:

temperature increases before and after the phase changes.

temperature increases before the phase change and decreases after the phase change.

temperature stays the same before and after the phase changes.

temperature decreases before and after the phase changes.

temperature decreases before the phase change and increases after the phase change.