Physics

The CGS system (centimeter-gram-second) is a variant of the metric system and is also known as the Metric or French system of units, as it originated in France and is based on metric units.

Historically, atoms were considered the smallest indivisible particles of matter, but modern physics has shown that atoms are divisible into smaller particles: electrons, protons, and neutrons. Protons and neutrons themselves are made of quarks. The truly indivisible particles known today are elementary particles such as quarks, leptons (including electrons), and gauge bosons, which are fundamental constituents of matter according to the Standard Model. Therefore, the atom is not the smallest indivisible particle, making option D ('None of these') the correct answer.

The mass-energy relation, expressed as E=mc², is a direct consequence of Einstein's Special Theory of Relativity, which relates mass and energy as interchangeable.

In semiconductors, electrical conductivity increases with temperature because more charge carriers are generated as temperature rises. In contrast, conductors typically show decreased conductivity with increasing temperature due to increased lattice vibrations.

Gamma rays are electromagnetic radiation and have no charge, so they are not deflected by electric or magnetic fields. Alpha and beta rays are charged particles and are deflected accordingly.

When two identical conducting spheres are connected by a wire, charges redistribute equally. Initially, charges are +2Q and -Q, total charge is +Q. After connection, each sphere has charge +Q/2. The force depends on the product of charges, so new force F' = k*(Q/2)*(Q/2)/r^2 = k*Q^2/4r^2, which is one-fourth the original force F. Hence, the force becomes F/4.

When a ball is thrown upwards and bounces back, the directions of displacement, velocity, and acceleration all change during the motion. Displacement changes as the ball moves up and then down, velocity changes direction at the peak, and acceleration due to gravity always acts downward, so its direction relative to velocity changes as well.

The triple point of water is a well-defined thermodynamic state where water coexists in solid, liquid, and vapor phases in equilibrium. According to authoritative sources including the National Institute of Standards and Technology (NIST) and scientific literature, the triple point of water occurs at a temperature of exactly 273.16 K (which is equivalent to 0.01 °C) and a pressure of approximately 611.657 Pa (about 0.611 kPa). Option C correctly states the temperature as 273.16 °C (which is a typographical error in the unit; it should be 273.16 K) and the pressure as 0.611 kPa, which matches the standard pressure value. Option D has the correct temperature unit (Kelvin) but an incorrect pressure value (750 kPa is far too high). Therefore, option C is the most accurate choice given the options, with the note that the temperature unit should be Kelvin, not Celsius. The triple point temperature is defined as 273.16 K, not °C.

The prefix 'Mega' in the metric system is represented by the symbol 'M', which denotes a factor of 10^6. Therefore, option C is correct.

The least count of a Vernier caliper is calculated as the difference between one main scale division (MSD) and one Vernier scale division (VSD). Typically, 10 Vernier scale divisions coincide with 9 main scale divisions. If one main scale division is 1 mm, then one Vernier scale division is 0.9 mm. Therefore, the least count = 1 mm - 0.9 mm = 0.1 mm. Hence, the correct least count is 0.1 mm, which corresponds to option C.