Question 1

An isotope,X,of a particular element has an atomic number of 15 and a mass number of 31.Therefore:

Accepted Answer

A) The atomic number of 15 matches the atomic number of phosphorus, so X is an isotope of phosphorus. 
B) The mass number of 31 minus the atomic number of 15 gives a neutron number of 16. 
C) The atomic mass of X can be calculated as 31 u, which is close to the atomic weight of phosphorus (30.97 u), but not exactly the same due to the presence of isotopes with different masses.

Question 2

Which of the following are incorrectly paired?

Accepted Answer

Phosphorus is represented by the symbol P, not Pr.

Question 3

The number of electrons in an atom is the same for all neutral atoms of that element.

Accepted Answer

The number of electrons in an atom is determined by the atomic number of the element, so all neutral atoms of the same element will have the same number of electrons.

Question 4

Which of the following atomic symbols is incorrect?

Accepted Answer

The answer of Which of the following atomic symbols is...

Question 5

An ion is formed

Accepted Answer

An ion is formed by either adding or subtracting electrons from the atom. This results in an imbalance between the number of protons and electrons in the atom, giving it a net positive or negative charge. Adding or subtracting protons or neutrons would change the identity of the atom and create a different element or isotope, respectively.

Question 6

Which of the following are incorrectly paired?

Accepted Answer

Cesium is incorrectly paired with the symbol Ce. The correct symbol for cesium is Cs.

Question 7

Which of the following are incorrectly paired?

Accepted Answer

O is not a halogen. It is a nonmetal. Halogens include fluorine, chlorine, bromine, iodine, and astatine.

Question 8

The numbers of protons,neutrons,and electrons in K⁺ are:

Accepted Answer

The answer of The numbers of protons,neutrons,and electrons in ...

Question 9

The formula of water,H₂O,suggests:

Accepted Answer

The formula H₂O suggests that there is one hydrogen (H) atom, represented by the symbol H, and one oxygen (O) atom, represented by the symbol O, in each molecule. The subscripts next to the H and O symbols indicate that each molecule has one of each atom. Therefore, there are two hydrogen atoms and one oxygen atom per water molecule, so choice B is the best answer. Choice A and C both suggest that one of the elements is more abundant in the molecule, but the formula does not support that. Choice D claims that there are two oxygen atoms per molecule, which is incorrect.

Question 10

Which among the following represent a set of isotopes? Atomic nuclei containing:
I.20 protons and 20 neutrons
II.21 protons and 19 neutrons
III.22 neutrons and 18 protons
IV.20 protons and 22 neutrons
V.21 protons and 20 neutrons

Accepted Answer

Isotopes have the same number of protons but different numbers of neutrons. The sets that have the same number of protons (20 or 21) are I, IV, and II, V. Among these, only I and IV have different numbers of neutrons, making them isotopes. Therefore, the correct answer is D, only I, IV, II, and V have isotopes.

Question 11

Which of the following are incorrectly paired?

Accepted Answer

H (Hydrogen) is not a noble gas; it is placed in Group 1 of the periodic table and is a nonmetal.

Question 12

Which of the following statements are true of uranium-238? I.
Its chemical properties will be exactly like those of uranium-235.
II.
Its mass will be slightly different from that of an atom of uranium-235.
III.
It will contain a different number of protons than an atom of uranium-235.
IV.
It is more plentiful in nature than uranium-235.

Accepted Answer

I. Uranium-238 and uranium-235 are isotopes, sharing the same chemical properties due to having the same number of protons.II. Uranium-238 has a slightly higher mass than uranium-235 because it has three more neutrons.IV. Uranium-238 is indeed more plentiful in nature than uranium-235, making up about 99.3% of natural uranium.

Question 13

The number of neutrons in an atom is the same for all neutral atoms of that element.

Accepted Answer

The number of protons in an atom determines the element, but the number of neutrons can vary among atoms of the same element, leading to different isotopes.

Question 14

Which of the following statements is true?

Accepted Answer

Solids are mostly open space due to the arrangement of atoms and the empty space between them. Ions are formed by adding or removing electrons, not protons. Heating water does not separate it into hydrogen and oxygen gases; it requires electrolysis.

Question 15

All of the following are true except:

Accepted Answer

Ions are formed by adding or removing electrons from a neutral atom, but changing the number of protons in an atom's nucleus would change the identity of the element and create a different atom, not an ion.

Question 16

A species with 12 protons and 10 electrons is

Accepted Answer

The element with 12 protons is magnesium (Mg). However, Mg typically has 12 electrons to balance the charge of the protons. The species described in the question has 10 electrons, indicating that two electrons have been lost (or possibly gained, if it is an ion). Therefore, the correct choice is C: Mg²⁺. The addition of sulfur (S) with a charge of -1 and phosphorus (P) with a charge of +1 balances the overall charge of the species and accounts for the missing two electrons. The notation "S1" and "P0" indicate the neutral form of these elements.

Question 17

By knowing the number of protons a neutral atom has,you should be able to determine

Accepted Answer

By knowing the number of protons, we can determine the atomic number of the element, which gives us information about the number of electrons in the neutral atom. We can also use the atomic number to determine the element's identity, which then allows us to determine the number of neutrons (by subtracting the atomic number from the mass number). Therefore, the correct answer is D: we can determine the number of electrons and the name of the atom by knowing the number of protons.

Question 18

Which of the following statements is (are)true?

Accepted Answer

The answer of Which of the following statements is (are)true?
...

Question 19

The element rhenium (Re)exists as two stable isotopes and 18 unstable isotopes.Rhenium-185 has in its nucleus

Accepted Answer

The answer of The element rhenium (Re)exists as two stable...

Question 20

Bromine exists naturally as a mixture of bromine-79 and bromine-81 isotopes.An atom of bromine-79 contains

Accepted Answer

Bromine-79 has an atomic number (number of protons) of 35, therefore it has 35 electrons. It also has a mass number of 79, which is the sum of protons and neutrons. To find the number of neutrons we subtract the atomic number from the mass number, giving us 79-35= 44 neutrons. Therefore, option A is the correct answer.

Quiz 2: Atoms, molecules, and Ions

An isotope,X,of a particular element has an atomic number of 15 and a mass number of 31.Therefore:

Which of the following are incorrectly paired?

The number of electrons in an atom is the same for all neutral atoms of that element.

Which of the following atomic symbols is incorrect?

An ion is formed

Which of the following are incorrectly paired?

Which of the following are incorrectly paired?

The numbers of protons,neutrons,and electrons in K⁺ are:

The formula of water,H₂O,suggests:

Which among the following represent a set of isotopes? Atomic nuclei containing: I.20 protons and 20 neutrons II.21 protons and 19 neutrons III.22 neutrons and 18 protons IV.20 protons and 22 neutrons V.21 protons and 20 neutrons

Which of the following are incorrectly paired?

The number of neutrons in an atom is the same for all neutral atoms of that element.

Which of the following statements is true?

All of the following are true except:

A species with 12 protons and 10 electrons is

By knowing the number of protons a neutral atom has,you should be able to determine

Which of the following statements is (are) true?

The element rhenium (Re) exists as two stable isotopes and 18 unstable isotopes.Rhenium-185 has in its nucleus

Bromine exists naturally as a mixture of bromine-79 and bromine-81 isotopes.An atom of bromine-79 contains

Quiz 2: Atoms, molecules, and Ions

An isotope,X,of a particular element has an atomic number of 15 and a mass number of 31.Therefore:

Which of the following are incorrectly paired?

The number of electrons in an atom is the same for all neutral atoms of that element.

Which of the following atomic symbols is incorrect?

An ion is formed

Which of the following are incorrectly paired?

Which of the following are incorrectly paired?

The numbers of protons,neutrons,and electrons in K+ are:

The formula of water,H2O,suggests:

Which among the following represent a set of isotopes? Atomic nuclei containing: I.20 protons and 20 neutrons II.21 protons and 19 neutrons III.22 neutrons and 18 protons IV.20 protons and 22 neutrons V.21 protons and 20 neutrons

Which of the following are incorrectly paired?

The number of neutrons in an atom is the same for all neutral atoms of that element.

Which of the following statements is true?

All of the following are true except:

A species with 12 protons and 10 electrons is

By knowing the number of protons a neutral atom has,you should be able to determine

Which of the following statements is (are) true?

The element rhenium (Re) exists as two stable isotopes and 18 unstable isotopes.Rhenium-185 has in its nucleus

Bromine exists naturally as a mixture of bromine-79 and bromine-81 isotopes.An atom of bromine-79 contains

The numbers of protons,neutrons,and electrons in K⁺ are:

The formula of water,H₂O,suggests: