The correct option is C.
An atom can be either in the ground state or in an excited state. An atom is said to be in the ground state, if the total energy of its electron can not be lowered by moving one or more electrons into different orbitals. At the ground state, the electrons in the atom have the lowest energy possible and they are stable. On the other hand, an atom is said to be in an excited state, if the energy of its electrons can be lowered by transferring one or more electrons into different orbitals. An atom in an excited state has more energy and is less stable.
Ion with a 1+ charge. The atom would normally be neutral, since it has the same number of electrons as it does protons; removing an electron leaves one more proton than electron. Since protons are positive and there's one more of them than electrons in the new ion, it has a 1+ charge.
Hi there!
Gravity from the sun is even and makes a planet orbit the sun by exerting a force that pulls the planet towards it. Since the gravity of the sun is always the same (or very, very similar), the planet's orbit stays the same.
Hope this helps!
To find average atomic mass, multiply each isotope's atomic mass with its relative abundance and add it all up.
15.012*0.1423 + 16.988*0.3348 + 19.177*0.5229 = 17.851 (5 s.f.)
