Me i beg you i really need !
what would be the overall charge on a substance composed of 19 protons, 18 electrons and 20 neutrons?

+1
0
-1
-2

which of the following statements is correct?

all atoms are electrically neutral.
all atoms are negatively charged.
all isotopes are positively charged.
all elements have an electrical charge.

which of the following statements correctly describes the relative size of the subatomic particles?

protons are the same size as neutrons, both are bigger than electrons
protons are the same size as electrons, both are bigger than neutrons
protons have the largest mass, and electrons and neutrons are similar in relative size
protons are the largest and most dense particles, electrons are dense but not very large, and neutrons are neither dense nor large in size

which subatomic particle is responsible for determining the identity of an element?

electron
proton
neutron
photon

all atoms of the same element have the same:

number of neutrons
atomic number
mass number
number of protons and neutrons

the nucleus of the atom is held together by the attraction of the positively charged protons and the negatively charged electrons.

true
false

the number of protons and neutrons in the nucleus of an atom must always be equal, in order for the strong nuclear force binding them together to be effective.

true
false

of the many theoretical contributions to the quantum theory, one of the contributions was the "uncertainty principle". which of the following statements describes the essence of this principle?

electrons exist in discrete energy levels, described by quantum numbers
energy must be added to move an electron to a level further away from the nucleus and removed to move an electron closer to the nucleus
radiant energy is quantized
due to the dual nature of electrons, we cannot simultaneously know an electron's position and its momentum (path). measuring one changes the other.

the schrödinger equation expresses the mathematical relationship between an electron's wave function and its total mechanical energy.

true
false

the total number of electrons that could be held in the 1s, 2s and 2 p orbitals, combined, is 12.

true
false