Question

14.the positively charged particle in the nucleus of an atom is the
a) electron.
b) magnetron.
c) neutron.
d) proton.
15.the number of protons in the nucleus of an atom is the
a) atomic number.
b) element number.
c) mass number.
d) atomic weight.
16.the sum of the protons and neutrons in the nucleus of an atom is the
a) atomic weight.
b) atomic number.
c) mass number.
d) element number.
17.the center of an atom is the
a) protons.
b) neutrons.
c) electrons.
d) isotopes.
e) nucleus.
18.the subatomic particle that is neutral is
a) a proton.
b) an isotope.
c) an electron.
d) a neutron.
e) a nucleus.
19.a negatively charged particle is
a) a nucleus.
b) an electron.
c) a neutron.
d) a proton.
20.how many protons are found in an atom of fluorine?
a) 9
b) 28
c) 19
d) 10
21.isotopes of an element have the same number of
a) neutrons, but different numbers of protons.
b) electrons, but different numbers of protons.
c) protons, but different numbers of neutrons.
d) protons, but different numbers of electrons.

Explanation:

• Question 14: Protons are positively - charged particles in the nucleus. Electrons are negatively - charged and outside the nucleus. Neutrons are neutral. Magnetron is not a sub - atomic particle in the nucleus.
• Question 15: The atomic number of an element is defined as the number of protons in the nucleus of its atom. Element number is not a standard term. Mass number is the sum of protons and neutrons. Atomic weight is a weighted average of isotopes' masses.
• Question 16: Mass number is calculated as the sum of protons and neutrons in the nucleus. Atomic weight is a weighted average. Atomic number is the number of protons. Element number is not a standard term.
• Question 17: The nucleus is the center of an atom. Protons and neutrons are in the nucleus, but they are not the center itself. Electrons are outside the nucleus. Isotopes are atoms of the same element with different neutron numbers.
• Question 18: Neutrons have no charge. Protons are positive. Electrons are negative. Isotopes are atoms, not sub - atomic particles. The nucleus is a part of an atom, not a sub - atomic particle.
• Question 19: Electrons are negatively - charged. Nucleus is positively - charged (due to protons). Neutrons are neutral. Protons are positive.
• Question 20: Fluorine has an atomic number of 9. Since the atomic number is equal to the number of protons, an atom of fluorine has 9 protons.
• Question 21: Isotopes of an element have the same number of protons (so they are the same element) but different numbers of neutrons. If the number of protons were different, they would be different elements. The number of electrons is usually the same as protons (for neutral atoms), but for isotopes, the difference is in neutrons.

Answer:

1. d) proton
2. a) atomic number
3. c) mass number
4. e) nucleus
5. d) a neutron
6. b) an electron
7. a) 9
8. c) protons, but different numbers of neutrons