These are four questions and four answers.
Question 1. Isotopes are considered stable when the strong force overcomes the electrostatic repulsion between positively charged _________
Answer: option B. protons.
Explanation:
1) The nuclei of the atoms are constitued by protons and neutros.
2) The neutrons does not have charge: they are neutral.
3) The protons are positively charged.
Since protons are packed together into a very tiny space, they exert an intense electrostatic repulsive force on each other, which is an unstable situation
The only way a nucleus remain stable is because there is other attractive force able to balance the repulsive electrostatic force. This other force is the strong nuclear force.
Question 2. An isotope is the same thing as which of the following?
Answer: option B. a nuclide
Explanation:
The word nuclide is used to refer to a specific kind of atom.
Remember that all the atoms of an element have the same number of protons but may differ in the number of neutrons.
Isotopes refers to the different varieties of atoms of a same element, this is atoms of a same element, with different number of neutron.
Nucilide names a specific kind of atom, i.e. the atom with its particular number of protons and neutrons (plus its nuclear energy state).
So, nuclide names a particular isotope of an element.
Question 3. Which term best completes the following statement?
Nuclei with ______ numbers of neutrons and protons are more stable.
Answer: option D. even.
Explanation:
The interaction between neutrons and protons in the nucleus is explained in terms of the quantum number named spin, which can be +1/2 or -1/2.
Paired spins and unpaired spins in a same region have different stabilities.
When the number of protons and neutrons in the same nucleus is even the spins can pair and so confere more stability.
That is way nuclei with even number of protons and neutrons are more stable.
Question 4. Which of the following is true of isotopes?
Answer: option B. Isotopes are two or more atoms with the same atomic number, but a different mass number.
Explanation:
1) Isotopes are specific kind of atoms of same element.
2) All the atoms of the same element have the same atomic number,which is the number of protons.
3) The isotopes differ in the number of neutrons.
4) The mass number is the number of protons plus the number of neutrons.
Therefore, the different isotopes differ in their mass number.
