Engineering Questions with Answers - Multiple Choice Questions
Materials Science MCQ ‘s – Atomic Structure Terminology
1 - Question
Species with the same number of neutrons but the different number of protons are called:
a) Isotones
b) Isotopes
c) Isomers
d) Isobars
View Answer
Explanation: Isotones are atoms of different elements having the same number of neutrons but different atomic and mass numbers. For e.g., Boron-12 and Carbon-12 are isotones each having 7 neutrons.
2 - Question
Atomic number of a species is the number of:
a) Neutrons
b) Protons
c) Valence electrons
d) Nucleons
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Explanation: Atomic number or the number of protons is the property that differentiates atoms of one species from another. For e.g., atomic numbers of Hydrogen and Helium are 1 and 2 respectively.
3 - Question
Oxygen gas is denser than Carbon Dioxide gas?
a) True
b) False
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Explanation: At any specified temperature, molar volume for every gas is the same. However, CO2(g) has higher molar weight than O2(g) which results in higher density.
4 - Question
Which of the following has the least number of atoms?
a) One gram of Hydrogen gas
b) One gram of Helium gas
c) One gram-mole of Oxygen gas
d) One gram-mole of Chlorine gas
View Answer
Explanation: One gram-mole of any gas contains Avogadro’s number of atoms/molecules. Hence, one gram-mole of Hydrogen gas and Helium gas weigh two grams and three grams respectively. 1g H2 = 1/2 g-mol H2; 1g He = 1/3 g-mol He. Thus, one gram of Helium has the least number of atoms.
5 - Question
Which of the following is not a pure form of matter?
a) Element
b) Compound
c) Solution
d) Both Compound and Solution
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Explanation: Different samples of the same element or compound will have an exactly same composition and hence both – element and compound are considered pure forms of matter.
6 - Question
Which if the following is not an SI unit?
a) Kilogram
b) Mole
c) Atomic Mass Unit
d) Coulomb
View Answer
Explanation: Because the SI unit of mass is a kilogram.
7 - Question
One unified atomic mass unit equals to ____________
a) 1/12 of molar mass of Carbon
b) 1/16 of atomic mass of Oxygen
c) 1/2 of the molecular mass of Hydrogen
d) all of the mentioned
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Explanation: 1 amu = 1/12 of atomic(not molar) mass of carbon = 1/16 of the atomic mass of Oxygen = 1/2 of molecular mass of Hydrogen.
8 - Question
Avogadro’s number of water molecules occupy 22.4 liters of space at 273 K.
a) True
b) False
View Answer
Explanation: Molar volume at 273 K is 22.4 liter, only for gases. However, at this temperature water does not exist as a gas.