Questions without answers in Materials Science

The band gap of a material is $E_{g}$ and the energy of an incident photon is $E_{p}$. Optical absorption will occur in this material if,$E_{g} < E_{p}$$E_{g}>E_{p}$Elect...

Discoloration and loss of mechanical strength of plastic chairs exposed to sunlight for several days is due toHydrophilic degradationOxidative degradationPhoto-degradatio...

Which of the following is/are polarization mechanisms in dielectric solids?Mechanical polarizationIonic polarizationElectronic polarizationThermal polarization

The degrees of freedom of a system with $2$ components and $2$ phases in equilibrium is $\_\_\_\_$ (answer in integer).

The equilibrium vacancy concentration in aluminum at $900$ $\mathrm{K}$ is $1.1 \times 10^{-4}$. The enthalpy of formation of vacancies in $\mathrm{kJ}. \mathrm{mol}^{-1}...

Three phases, $\alpha, \beta$ and $\mathrm{L}$ are shown in the binary phase diagram below. Identify the correct $\mathrm{G-X}$ (Gibbs free energy vs Composition) plot co...

In a cubic crystal, the Burgers vector for a mixed dislocation line is $\dfrac{a}{2}$ $[110]$. The dislocation line lies along the $[011]$ direction. The slip plane of th...

Which one of the following statements regarding point defects in ionic solids is correct?Frenkel defects are dominant in those ionic solids where there is a considerable ...

Consider $3$ crystals (all having FCC lattice) labelled as $\text{P, Q}$ and $\text{R}$ as described below:Crystal $\text{P}$: Cu crystal with $4$ $\text{Cu}$ atoms per u...

According to quantum free electron theory, which of the following statements is/are correct regarding the behavior of valence electrons in a metal?Valence electrons are l...

$\mathrm{Fe}$ has a density of $7.87 \mathrm{~g} . \mathrm{cm}^{-3}$, atomic mass of $55.84 \mathrm{~g} . \mathrm{mol}^{-1}$ and net magnetic moment per atom of $2.22$ Bo...

A $1 \mathrm{~cm}^{3} \mathrm{~Si}$ cube is doped with As with a concentration of $1$ atom per $10^{9} \mathrm{~Si}$ atoms. The resistance of the doped $\mathrm{Si}$ cube...

A stream of moist air at $101$ $\mathrm{kPa}$ and $25^{\circ} \mathrm{C}$ undergoes a constant pressure process such that its dry bulb temperature increases and specific ...

Consider a single component fluid at saturation conditions having the following properties.Latent heat of vaporization, $h_{f g}=39.6 \times 10^{3} \mathrm{~kJ} / \mathrm...

A rigid spherical solid ball at $1000^{\circ} \mathrm{C}$ is cooled slowly to $200^{\circ} \mathrm{C}$ in a surrounding air at $25^{\circ} \mathrm{C}$. The density, speci...

Which of the following polymers is/are prone to hydrolytic degradation?Poly(ethylene terephthalate)PolypropylenePoly(lactic acid)Polycaprolactone

A fuel with composition by mass is given as $78 \%$ carbon $(\mathrm{C}), 16 \%$ hydrogen $\left(\mathrm{H}_{2}\right)$, $3.2 \%$ sulphur $(\mathrm{S}), 1.6 \%$ oxygen $\...

Which of the following options is/are true regarding the behaviour of a typical solar photovoltaic cell?Ideal current sourceCurrent limited voltage sourceVoltage limited ...

​​​​The figure below shows a plane $\text{PQR}$ in a unit cell. The Miller indices of the plane $\text{PQR}$ is$(432)$$(43 \overline{2})$$(23 \overline{4})$$(\overline{2}...

​​​​​The unit of measurement for magnetic dipole moment of a body is$\mathrm{A} \: \mathrm{m}^{2}$$\mathrm{A} \: \mathrm{m}^{-1}$$\mathrm{Wb} \: \mathrm{m}^{-2}$$\mathrm{...