JUNE 2023 CHEMISTRY REGENTS Q&A PART A

Which phrase describes the nucleus of any atom?

has an overall positive charge

Which two particles each have a mass of approximately one atomic mass unit?

a neutron and a proton

The wave-mechanical model of the atom describes the location of electrons

in orbitals outside the nucleus

When a ground state electron in an atom moves to an excited state, the electron

absorbs energy as it moves to a higher energy state

Which statement describes a chemical property of iron?

Iron reacts with nitric acid.

Diamond and graphite are two forms of solid carbon. These two forms of carbon have

different crystal structures and different properties

Which substance can be broken down by a chemical change?

ethane

At STP, which property can be used to differentiate a 10.-gram sample of NaCl(s) from a 10.-gram sample of NaNO3(s)?

solubility in water

What is the number of electrons shared between the two atoms in an O2 molecule?

4

Which changes in both charge and radius occur when an atom loses an electron?

A positive ion is formed with a smaller radius than the atom

Which statement describes what occurs when two iodine atoms react to produce an iodine molecule?

A bond breaks and energy is absorbed.

Which process can be used to separate a mixture of two liquids having different boiling points?

distillation

Which statement describes a solution of sodium chloride in water?

The mixture is homogeneous, the solute is NaCl and the solvent is H2O.

At STP, which property would be the same for 1.0 liter of helium and 1.0 liter of argon?

number of atoms

The melting of an ice cube is an example of an

endothermic, physical change

Which statement explains the low boiling point of hydrogen, H2, at standard pressure?

Hydrogen has weak intermolecular forces.

In chemical reactions, which term is defined as the difference between the potential energy of the products and the potential energy of the reactants?

heat of reaction

Which phrase describes what happens to the reaction pathway and activation energy of a reaction to which a catalyst is added?

a different pathway with a lower activation energy

An atom of which element is bonded to the carbon atom in the amide functional group?

nitrogen

Which statement describes the two isomers of butane?

They have the same molecular formula but different structural formulas.

Which term represents an organic reaction that produces soap?

saponification

In which part of an electrochemical cell does reduction occur?

cathode

Which energy change occurs in an operating voltaic cell?

chemical energy to electrical energy

Which substance is an Arrhenius base?

LiOH

Which statement represents neutralization?

An Arrhenius acid and an Arrhenius base react to produce water and a salt.

A tenfold increase in hydronium ion concentration is represented by

a decrease of one unit of pH

Based on Table N, which particle is emitted by the radioactive decay of francium-220?

an alpha particle

Which type of reaction releases the greatest amount of energy per kilogram of reactant?

fission reaction

Which risk is related to the radioactive isotopes used to generate electricity?

exposure to nuclear emmisions