NEET Practice Questions (MCQs) with Answers & Solutions

The NCERT states, 'semiconductor doped with pentavalent impurity, electrons become the majority carriers... These semiconductors are, therefore, known as n -type semiconductors.' And, 'the donor energy level ED is slightly below the bottom EC of the conduction band and electrons from this level move into the conduction band with very small supply of energy.' The donor atoms 'donate' these electrons.

The NCERT says 'an electron from the valence band can jump to the level EA and ionise the acceptor negatively. (Alternately, we can also say that with very small supply of energy the hole from level EA sinks down into the valence band.) At room temperature, most of the acceptor atoms get ionised leaving holes in the valence band.' This process leaves holes in the valence band.

The NCERT states, 'For C (diamond), Si and Ge, the energy gaps are 5.4 eV, 1.1 eV and 0.7 eV, respectively.' This shows Ge has the smallest, then Si, then C.

The NCERT text mentions, 'Electrons rise up and holes fall down when they gain external energy.'

According to the NCERT text (Chapter: THERMAL_PROPERTIES_OF_MATTER, Section 10.4; Chapter: KINETIC_THEORY, Summary point 1), the ideal gas equation relating pressure (P), volume (V), and absolute temperature (T) is given by PV = µRT, where µ is the number of moles and R is the universal gas constant.

The NCERT text (Chapter: THERMAL_PROPERTIES_OF_MATTER, Section 10.4, and Chapter: KINETIC_THEORY, Summary point 1) states that the universal gas constant R = 8.31 J mol⁻¹ K⁻¹.

The NCERT text (Chapter: KINETIC_THEORY, Section 12.3 and Summary point 1) mentions, 'Real gases satisfy the ideal gas equation only approximately, more so at low pressures and high temperatures.' Also, 'At low pressures or high temperatures the molecules are far apart and molecular interactions are negligible. Without interactions the gas behaves like an ideal one.'

According to Boyle's Law, derived from the ideal gas equation (PV = constant if µ and T are fixed), if temperature is constant, the product of pressure and volume remains constant (Chapter: KINETIC_THEORY, Section 12.3).

The NCERT text (Chapter: KINETIC_THEORY, Section 12.3) states, 'if you fix P, Eq. (12.1) shows that V ∝ T i.e., for a fixed pressure, the volume of a gas is proportional to its absolute temperature T (Charles’ law).'

The NCERT text (Chapter: KINETIC_THEORY, Section 12.4.2) states, 'the average kinetic energy of a molecule is proportional to the absolute temperature of the gas [from E/N = (1/2)m <v^2> = (3/2)k_B T]'. This is a fundamental result.