MCQs on Engineering Materials

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01․ Which of the following statements is not part of Daltons atomic theory?
All matter is composed of atoms.
Atoms can combine to form compounds.
Atoms of different elements are quite different.
An atom contains a dense central nucleus.

The Dalton’s atomic theory is not dealing with dense central nucleus.

02․ Two different isotopes of an element have different
numbers of neutrons.
numbers of electrons.
atomic number.
numbers of protons.

Two different isotopes have different neutrons and they have same number of protons. Thus, they have different mass numbers. This means that they differ in the number of neutrons but being the same element.

03․ Which of the following statements is not true?
A s orbital can hold two electrons.
A d orbital can hold ten electrons.
A f orbital can hold three electrons.
A p orbital can hold six electrons.

An atomic orbital is the concept used to describe the behavior of electrons in the atom. It is commonly used to determine where an electron can be found as it surrounds the nucleus of the atom. Each of the four orbital holds a varied number of electrons. The S orbital holds 2 electrons, the P orbital holds 6 electrons, the D orbital holds 10 electrons and the F orbital holds 14 electrons.

04․ The electron configuration of copper is
1s2 , 2s2 2p6, 3s2 3p6 3d8, 4s1 4p<
1s2 , 2s2 2p6, 3s2 3p6 3d10, 4s1.
1s2 , 2s2 2p6, 3s2 3p6 3d9, 4s2.
none of above.

Copper has totally 29 electrons. The electron configuration is 2 + 8 + 18 + 1 = 29. We can write as 2 +(2 + 6) + (2 + 6 + 10) + 1.

05․ The electron configuration of sulfur atom is
2, 8, 6.
1s2 , 2s2 2p6, 3s2 3p6.
2, 8, 2.
none of these.

1s2, 2s2 2p6, 3s2 3p4 is the electron configuration of sulfur atom. Then 2, 8, 6 would match the 2 electrons in level 1, the 8 electrons in level 2 and the 6 electrons in level 3.

06․ In Bohr’s model of atomic structure, the nucleus consists of
electrons and protons.
protons and neutrons.

As per Bohr’s planetary model of atom, the mass of an atom is concentrated in a central nucleus which mainly consists of protons and neutrons.

07․ The atomic radius in case of face centered cubic lattice is
a / 2.
a / 3.
a / 4.

The unit cell for the simple cubic structure contains one-eighth portions of eight corner atoms to make one complete atom, molecule or ion in each unit cell. Given the radius of the atom or ion the edge length is just; edge length (a) = 2r; where r is the radius of the atom or ion.

08․ The materials which exhibit the same elastic properties in all directions are called
visco elastic.

Isotropy is uniformity in all orientations; it is derived from the Greek isos ( equal ) and tropos ( manner ).

09․ Permittivity of free space is equal to
8.854 × 10 - 12 F / m.
8.854 × 10 - 13 F / m.
8.854 × 10 - 11 F / m.
8.854 × 10 - 10 F / m.

Permitivity of free space is equal to 8.854 × 10 - 12 F / m.

10․ Absolute permittivity of a dielectric medium is represented by
εo / εr.
εr / εo.
none of the above.

The absolute permittivity of a dielectric medium is expressed as ε = εoεr Where, εo is the permittivity of free space and εr is the relative permittivity of the medium.