Chemistry Regents Practice

According to the wave-mechanical model, in the ground state, the 10 electrons of a neon atom would be located

• in the nucleus

• in orbitals

• in the first shell

• in the valence shell

Answer explanation

Orbital: A region of space within an atom where an electron in a given subshell can be found.

Which statement describes two different isotopes of carbon?

• The isotopes contain the same number of neutrons and have the same atomic number.

• The isotopes contain the same number of neutrons but have a different atomic number

• The isotopes contain a different number of neutrons but have the same atomic number.

• The isotopes contain a different number of neutrons and have a different atomic number.

Answer explanation

Isotope, one of two or more species of atoms of a chemical element with the same atomic number and position in the periodic table and nearly identical chemical behavior but with different atomic masses and physical properties

Tags

NGSS.HS-PS1-8

An element that is a very reactive metal could have an atomic number of

• 9

• 2

• 19

• 79

Answer explanation

The most reactive metals have the greatest tendency to lose electrons to form positively charged ions. Metals, therefore, become more reactive as they are located further to the left on the periodic table.

You can also reference Table J (Activity Series) in your Chemistry Reference Table.

Tags

NGSS.HS-PS1-1

NGSS.HS-PS1-2

Which element is listed with the number of protons in each of its atoms?

• nitrogen, 14

• silicon, 14

• oxygen, 16

• phosphorus, 16

Answer explanation

The number of protons in the nucleus of the atom is equal to the atomic number (Z).

The number of electrons in a neutral atom is equal to the number of protons.

The mass number of the atom (M) is equal to the sum of the number of protons and neutrons in the nucleus.

Tags

NGSS.HS-PS1-1

What is the overall charge on the nucleus of a fluorine atom?

• -1

• -9

• +9

• +19

Answer explanation

• An atomic nucleus consists of positively charged particles (protons) and uncharged particles (neutrons).

• An atom is composed of a positively charged nucleus, and electrons revolving around it in defined circular orbits.

• The nucleus is very small/dense when compared to the rest of the atom.

Tags

NGSS.HS-PS1-1

As the elements with atomic numbers 11 through 17 are considered in order of increasing atomic number, the classification of the elements changes from

• metal to metalloid to nonmetal

• metal to nonmetal to metalloid

• nonmetal to metalloid to metal

• nonmetal to metal to metalloid

Answer explanation

• Metalloids are also known as semi metals.

• They are a group of metals that lie between metals and non-metals.

• They form alloys with metal.

• They are solid at room temperature.

• They show the properties of metals and non-metals.

Tags

NGSS.HS-PS1-1

A compound consists of two or more different elements that are

• physically mixed in a fixed proportion

• physically mixed in a proportion that can vary

• chemically combined in a fixed proportion

• chemically combined in a proportion that can vary

Answer explanation

Compounds are chemical substances made up of two or more elements that are chemically bound together in a fixed ratio.

Which atom forms an ion with a radius larger than the atomic radius?

• calcium atom

• oxygen atom

• lead atom

• tin atom

Answer explanation

The atomic size of a cation (Positive Ion) will be smaller than that of the parent atom.

An anion (Negative Ion) is relatively larger in size than its parent atom.

Which sample can be classified as a substance?

• air

• argon

• soil

• seawater

Answer explanation

Pure substances are substances that are made up of only one kind of particle and have a fixed or constant structure.

Pure substances are further classified as elements and compounds.

Based on Table G, which compound has the greatest solubility in 100. grams of water at 10.°C?

• HCl

• NaCl

• KCl

• NH4Cl

Answer explanation

Table G is titled as Solubility Curves at Standard Pressure. The x-axis title is Temperature and the y-axis is Solubility (g solute/100. g H2O).

This chart shows us how much of each substance dissolves in 100g of water, emphasis on 100 grams, at different temperatures