Chemistry Exam 2 Practice

Atoms that have the same number of protons but different numbers of neutrons.

• Isotopes

• Molecules

• Compounds

• Elements

Answer explanation

Isotopes are atoms that have the same number of protons but different numbers of neutrons. This definition distinguishes them from molecules, compounds, and elements, making 'Isotopes' the correct answer.

How does the energy of an electron change when the electron moves closer to the nucleus?

• The energy of the electron fluctuates randomly.

• The energy of the electron remains the same.

• The energy of the electron decreases.

• The energy of the electron increases.

Answer explanation

As an electron moves closer to the nucleus, it is attracted by the positive charge of the nucleus, which lowers its potential energy. Therefore, the energy of the electron decreases.

Tags

NGSS.HS-PS1-2

The second energy level (“n = 2”) can hold how many electrons?

• 8

• 10

• 4

• 2

Answer explanation

The second energy level (n = 2) can hold a maximum of 2n² electrons. Substituting n = 2 gives 2(2)² = 8. Therefore, the correct answer is 8.

How many suborbitals are there for the p-orbital?

• 3

• 4

• 1

• 2

Answer explanation

The p-orbital has three suborbitals, designated as p_x, p_y, and p_z. Each suborbital can hold a maximum of two electrons, making the total number of suborbitals for the p-orbital equal to 3.

Which of the following electron transitions would be associated with the greatest energy of emitted light?

• Transition from n=1 to n=2

• Transition from n=4 to n=1

• Transition from n=4 to n=3

• Transition from n=4 to n=5

Answer explanation

The transition from n=4 to n=1 involves a larger energy difference than the other transitions, resulting in the emission of light with the greatest energy. Higher energy transitions correspond to larger differences in principal quantum numbers.

Tags

NGSS.HS-PS1-4

What form of radioactive decay involves a neutron splitting to form a proton and negative charge.

• Beta decay

• Alpha decay

• Gamma decay

• Neutron capture

Answer explanation

Beta decay occurs when a neutron splits into a proton and an electron (negative charge). This process increases the atomic number of the element, making beta decay the correct answer.

Tags

NGSS.HS-PS1-8

Which form of radiation involves high energy and is often associated with nuclear reactions.

• Alpha particles

• Gamma rays

• X-rays

• Beta particles

Answer explanation

Gamma rays are a form of high-energy radiation commonly emitted during nuclear reactions. Unlike alpha and beta particles, which are charged, gamma rays are uncharged electromagnetic waves, making them highly penetrating.

Tags

NGSS.HS-PS1-8

What is the charge of the atom ¹⁹F^-1

• -1

• +1

• 0

• +2

Answer explanation

The atom is represented as 19F^-1, indicating it has a negative charge of -1. This means it has one more electron than protons, resulting in an overall charge of -1.

How many neutrons are in the atom ³⁶Cl^-1

• 17

• 21

• 18

• 19

Answer explanation

To find the number of neutrons in 36Cl-1, subtract the atomic number (17) from the mass number (36). Thus, 36 - 17 = 19 neutrons. The correct answer is 19.

How much energy is in a radiation with a frequency of 3.45x10¹² Hz?

• 5.64 x 10^-19 J

• 3.00 x 10^-22 J

• 2.29 x 10^-21 J

• 1.5 x 10^-20 J

Answer explanation

The energy of radiation can be calculated using the formula E = h * f, where h is Planck's constant (6.626 x 10^-34 J·s) and f is the frequency. For 3.45 x 10^12 Hz, E = 6.626 x 10^-34 * 3.45 x 10^12 = 2.29 x 10^-21 J.

Tags

NGSS.HS-PS4-1

NGSS.HS-PS4-3