The Correct Answer is Option (B)

Electrical conductivity is a measure of a material's ability to conduct an electric current. The higher the conductivity, the lower the resistivity. So, if we are looking for the material with the smallest resistivity, we are looking for the material with the highest electrical conductivity. Among the options given, silver (Option B) is known to have the highest electrical conductivity and thus, the smallest resistivity. Germanium (Option A) and silicon (Option D) are semiconductors, meaning they have moderate conductivity that can be manipulated, while glass (Option C) is generally a poor conductor, or an insulator. Therefore, silver is the correct answer.

The Correct Answer is (D)

For p type semiconductor trivalent impurity added

The Correct Answer is (C)

As the temperature increases the resistivity of the conductor increases hence the electrical resistance increases. However for semiconductor the resistivity decreases with the temperature. Hence electrical resistance of semiconductor decreases.

The Correct Answer is (D)

In N type semiconductor majority charge carriers are e^$-$ and P type semiconductor majority charge carriers are holes.

I = neAV_d = neA ($\mu$E)

As $\mu$_e >$\mu$_h $\Rightarrow$ I_e > I_h

The Correct Answer is (A)

In p-type semiconductor, an intrinsic semiconductor is doped with trivalent impurities, that creates deficiencies of valence electrons called holes which are majority charge carriers.

The Correct Answer is (A)

In n-type semiconductor, electrons are majority charge carriers and holes are minority charge carriers and pentavalent atoms are dopants.

The Correct Answer is (C)

Electronic configuration of ⁶C

⁶C = 1s², 2s² 2p²

The electronic configuration of ¹⁴Si

¹⁴Si = 1s², 2s² 2p⁶, 3s² 3p²

As they are away from Nucleus, so effect of nucleus is low for Si even for Sn and Pb are almost mettalic.

The Correct Answer is (A)

(n_i)² = n_e × n_h

(1.5 × 10¹⁶)² = n_e (4.5 × 10²²)

So n_e = 5 × 10⁹

Now n_h = 4.5 × 10²²

$\Rightarrow$ n_h $>>$ n_e

Hence, semiconductor is p-type

and n_e = 5 × 10⁹ m^–3

The Correct Answer is (C)

If a small amount of antimony is added to germanium crystal, crystal becomes n-type semiconductor. Hence, there will be more free electrons than holes.

The Correct Answer is (B)

In a n-type semiconductors, electrons are majority carriers and holes are minority carriers.

The Correct Answer is (A)

In case of metal, conductivity decreases with increase in temperature and metal has high melting point.

The Correct Answer is ()

Distance between nearest atoms in body centred cubic lattice (bcc),

d = $\frac{\sqrt{3}}{2}a$

Given d = 3.7 $\stackrel{\circ }{A}$

$\therefore$$a=\frac{3.7\times 2}{\sqrt{3}}$ = 4.3 $\stackrel{\circ }{A}$

The Correct Answer is (B)

The atomic radius in a f.c.c. crystal is = $\frac{a}{2\sqrt{2}}$

$\therefore$ Atomic radius =$\frac{3.6}{2\sqrt{2}}$ = 1.27 $\stackrel{\circ }{A}$

The Correct Answer is (D)

For a p-type semiconductor, the acceptor energy level, as shown in the diagram, is slightly above the top E_v of the valence band. With very small supply of energy an electron from the valence band can jump to the level E_C and ionise acceptor negatively.

The Correct Answer is (C)

In a cubic crystal structure
a = b = c  and  $\alpha$ = $\beta$ = $\gamma$ = 90^o

The Correct Answer is Option (C)

Option (a) is correct as in conductor conduction and valance band overlap and the conduction band is partially filled

Option (b) is correct as insulators have energy gap of 5 - 10 eV.

Option (c) is incorrect as resistivity decreases with increase in temperature.

Option (d) is correct as with increase in temperature, more and more electrons jump to conduction band, hence conductivity increases.

The Correct Answer is Option (A)

Band gap of carbon is 5.5 eV while that of silicon is 1.1 eV

$\therefore$ (E_g)_C $>$ (E_g)_Si

The Correct Answer is Option (B)

Lattice constant for (f.c.c.)

= a = interatomic spacing $\times$$\sqrt{2}$ = 3.59 $\stackrel{\circ }{A}$

The Correct Answer is Option (A)

In semiconductors at room temperature the electrons get enough energy so that they are able to over come the forbidden gap. Thus at room temperature the valence band is partially empty and conduction band is partially filled. Conduction band in semiconductor is completely empty only at 0 K.

The Correct Answer is Option (C)

In body-centred cubic (b.c.c.) lattice there are eight atoms at the corners of the cube and one at the centre.

Therefore number of atom per unit cell

=$\frac{1}{8}\times 8$ + 1 = 2

The Correct Answer is Option (B)

In an Ionic crystal, the cations and anions are arranged in alternate form.