physics : class12 Atomic Mass : Mass Defect : Atoms and Nuclei MCQ Questions and Answers
Practice important
Atomic Mass
MCQ questions and answers.
Page 1
of
1
|
10
MCQ Questions
1. The atomic mass of an atom is usually expressed in which unit?
A.
Atomic mass unit
B.
Ampere
C.
Kelvin
D.
Newton
Correct Answer:
Atomic mass unit
Explanation:
Atomic masses are commonly measured in atomic mass units, abbreviated as u or amu.
2. One atomic mass unit is defined as one-twelfth of the mass of which atom?
A.
Hydrogen-1
B.
Carbon-12
C.
Oxygen-16
D.
Helium-4
Correct Answer:
Carbon-12
Explanation:
One atomic mass unit is defined as one-twelfth of the mass of a neutral carbon-12 atom.
3. The approximate value of one atomic mass unit in kilograms is:
A.
1.66 × 10^-27 kg
B.
9.11 × 10^-31 kg
C.
1.60 × 10^-19 kg
D.
6.02 × 10^23 kg
Correct Answer:
1.66 × 10^-27 kg
Explanation:
The atomic mass unit has a mass of approximately 1.66 × 10^-27 kg.
4. The atomic mass of an element having two isotopes is generally:
A.
The mass of its lightest isotope
B.
The mass of its heaviest isotope
C.
The weighted average of the isotope masses
D.
Always exactly equal to its mass number
Correct Answer:
The weighted average of the isotope masses
Explanation:
The atomic mass of an element is calculated as the weighted average of the masses of its naturally occurring isotopes.
5. The mass number of an atom is always:
A.
A whole number
B.
A decimal number
C.
Less than zero
D.
Equal to the atomic mass in kilograms
Correct Answer:
A whole number
Explanation:
Mass number is the total number of protons and neutrons, so it is always a whole number.
6. Which statement correctly describes atomic mass and mass number?
A.
Atomic mass is usually a weighted average, while mass number is an integer
B.
Both are always identical integers
C.
Atomic mass is measured in amperes, while mass number is measured in kilograms
D.
Mass number depends on the natural abundance of isotopes
Correct Answer:
Atomic mass is usually a weighted average, while mass number is an integer
Explanation:
Atomic mass can be fractional because it is often an isotope-weighted average, whereas mass number is the integer sum of protons and neutrons.
7. The atomic mass of an isotope is approximately equal to its mass number when expressed in:
A.
Atomic mass units
B.
Coulombs
C.
Joules
D.
Metres
Correct Answer:
Atomic mass units
Explanation:
The mass of an individual isotope is approximately equal to its mass number in atomic mass units.
8. An element has two isotopes with masses 10 u and 11 u. If the isotope of mass 10 u is more abundant, the average atomic mass will be:
A.
Less than 10 u
B.
Between 10 u and 11 u, closer to 10 u
C.
Exactly 11 u
D.
Greater than 11 u
Correct Answer:
Between 10 u and 11 u, closer to 10 u
Explanation:
The weighted average lies between the isotope masses and is closer to the mass of the more abundant isotope.
9. The atomic mass of a neutral atom includes the masses of its:
A.
Protons, neutrons, and electrons
B.
Protons only
C.
Neutrons only
D.
Electrons only
Correct Answer:
Protons, neutrons, and electrons
Explanation:
The atomic mass of a neutral atom includes its nucleus and its surrounding electrons.
10. Which of the following is a commonly used symbol for the atomic mass unit?
A.
u
B.
A
C.
N
D.
K
Correct Answer:
u
Explanation:
The atomic mass unit is commonly represented by the symbol u; amu is also widely used.
Short Questions and Answers
Practice short questions and answers related to
Atomic Mass
.
Short questions are currently unavailable for this page.