Physics

A Geiger counter is best suited for slow counting rates because it has a limited resolving time and cannot accurately measure very high or extremely fast counting rates without significant dead time losses.

Alpha particles, which are helium nuclei, interact with atoms primarily by ionizing them. This ionization process involves knocking out electrons from the atom, not protons or neutrons. Protons and neutrons are bound tightly within the nucleus and are not typically knocked out by alpha particles during ordinary encounters. Alpha particles have enough energy to remove electrons from atoms, causing ionization, but they do not generally dislodge nucleons (protons or neutrons) unless in specific nuclear reactions or high-energy collisions, which are not the usual context of the question.

Neutrons and protons are collectively known as nucleons because they both reside in the nucleus of an atom. This term distinguishes them from other particles like mesons, bosons, or quartz, which are unrelated to nucleons.

For a chain reaction to sustain and build up, the size of the radioactive target must be greater than the critical size. This ensures enough neutrons are produced and maintained to continue the reaction.

Antimatter is composed of antiparticles corresponding to normal matter particles, including antiprotons, antineutrons, and positrons. Therefore, all the listed particles are components of antimatter.

The dimensional formula ML⁻¹T⁻² corresponds to force per unit area, which is the dimension of pressure. Force has the dimension ML¹T⁻², and dividing by area (L²) gives ML⁻¹T⁻². This dimension also corresponds to energy per unit volume, but among the given options, pressure is the correct match. Momentum has the dimension MLT⁻¹, energy has ML²T⁻², and force has ML¹T⁻², so they do not match ML⁻¹T⁻².

Options B and C both represent the same vector with components (1/√3) along each axis, which has a magnitude of 1, making it a unit vector. Option A has components √3, which results in a magnitude greater than 1, so it is not a unit vector.

Alpha particles are positively charged and relatively heavy, so when they move in a uniform electric or magnetic field, their path is generally straight (rectilinear) unless acted upon by external forces. They do not move in zig-zag or erratic paths under normal conditions.

Cadmium rods are used in nuclear reactors as control rods because cadmium has a high neutron absorption cross-section, which helps control the fission chain reaction by absorbing excess neutrons.

Uncertainty in measurement can arise from multiple sources including the limitations of the measuring instrument, natural variations in the object being measured, and inadequate measurement techniques. Therefore, all options A, B, and C contribute to measurement uncertainty.