Answer
a. This statement is true.
b. This statement is false. The correct statement should be, "The isotope of X contains 34 protons."
c. This statement is false. The correct statement should be, "The isotope of X contains 45 neutrons."
d. This statement is false. The correct statement should be, "The identitiy of X is selenium, Se."
Work Step by Step
a. This statement is true. Protons are positively charged particles whereas electrons are negatively charged particles. Each proton's positive charge cancels out the negative charge of an electron. If an ion has a net negative charge, that means that it has more electrons than it has protons.
b. This statement is false. If the ion has a -2 charge, that means that there are two more electrons than there are protons. If there are 36 electrons, then the ion has only 34 protons, thus creating the -2 charge. The correct statement should be, "The isotope of X contains 34 protons."
c. This statement is false. If we have determined that this ion has 34 protons, we can subtract this number from the mass number of 79 to get the number of protons because an atom's mass number is the number of protons and neutrons in its nucleus. If we subtract the number of protons from the mass number, we find that the number of neutrons in this particular isotope is 45. The correct statement should be, "The isotope of X contains 45 neutrons."
d. This statement is false. Because the number of protons in an atom is also its atomic number, the atomic number of this element is 34, which is not strontium but selenium, Se. The correct statement should be, "The identitiy of X is selenium, Se."
