Question Detail

CHM 101 CHM 101 Past Questions Objective Question
Take CBT

Question

How many protons, neutrons, and electrons are present in the isotope ³⁹₁₉K?
Options
A 19 protons, 20 neutrons, 19 electrons
Correct Answer
B 19 protons, 19 neutrons, 20 electrons
C 20 protons, 19 neutrons, 20 electrons
D 19 protons, 19 neutrons, 18 electrons
Correct Answer

Option A is the correct answer.

Detailed Explanation

In the notation ³⁹₁₉K, the subscript (19) is the atomic number, which equals the number of protons (19). In a neutral atom, the number of electrons also equals the number of protons, so electrons = 19. The superscript (39) is the mass number (protons + neutrons). Therefore, neutrons = 39 - 19 = 20.

Hint

Atomic number (Z) = protons = electrons. Mass number (A) = protons + neutrons.

Question Info

Course: CHM 101
Topic: CHM 101 Past Questions
Type: Objective
Difficulty: Not specified
Question 394 of 1872
Previous Course Details Next