# Objective Questions on Atomic Structure | 5

1. The electron is lighter than a proton by a factor of about

The mass of electron is 9.109 × 10 - 31 kg,
whereas the mass of a proton is 1.672 × 10 - 27 kg.
The ratio of their mass will be $\frac{1.672 \times 10^{- 27}kg}{9.109 \times 10^{-31}kg}\approx 1840$

2. The charge of an electron is

The charge of an electron is - 1.602 × 10 - 19 Coulombs

3. The mass of a proton is

A proton carries a positive charge and its mass is 1.672 x 10 - 27 kg.

4. The mass of a neutron of atom is

A neutron carries no charge and its mass is 1.675 × 10 - 27 kg.

5. In Bohr’s model of atomic structure, the nucleus consists of

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.

6. The atomic radius in case of face centered cubic lattice is

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.

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

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

8. Which of the following is the heaviest?

Molecule contains atom - atom contains electrons and protons.

9. Germanium has

A covalent bond is the chemical bond that involves the sharing of pairs of electrons between atoms. In the electronic configuration of germanium crystals there are four valence electrons. These four electrons will form covalent bonds, with the neighboring electrons of the germanium atoms. Each covalent bond is formed by sharing each electron from the each atom. After bond formation, no free electron will remain in the outermost shell of the germanium semi conductor.

10. Energy gap of conductor is

Energy gap is the gap between conduction band and valance band. Energy gap Eg of conductor is 0 eV since it has overlapped valance and conduction band.

11. Energy gap of semiconductor is approx

Energy gap is the gap between conduction band and valance band. Energy gap Eg of the semiconductor is relatively small around 1 eV.

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