The correct answer is a and b are universally true. Explanation & Key Takeaways: • Beta particles are negatively charged and are more penetrating than Alpha particles, which are positively charged. • Gamma particles are neutral and are more penetrating than Beta-particles. • Hence a and b are universally true. Important Notes: +-------------------+--------------------+--------------------+--------------------------+ | Property | Alpha Ray | Beta ray | Gamma Ray | +-------------------+--------------------+--------------------+--------------------------+ | Nature | Positive charge(+) | Negative Charge(-) | Neutral | | Charge | +2e | -e | 0 | | Range | up to 10 cm | up to a few meters | Several meters | | Can be stopped by | Paper sheet | Aluminium sheet | Thick lead sheet(2 feet) | +-------------------+--------------------+--------------------+--------------------------+ Related Concepts: Alpha Rays • Alpha rays are positively charged particles. • Alpha-particle is a highly active and energetic helium atom. • These particles have the minimum penetration power and highest ionization power. • It is due to the fact that the radioactive substances that release alpha particles are required to be handled after wearing rubber gloves. Beta Rays • Beta particles are extremely energetic electrons released from the inner nucleus. • They bear negligible mass and carry a negative charge. • A neutron in the nucleus splits into a proton and an electron on the emission of a beta particle. • Beta particles have a higher penetration power when compared to alpha particles. • Beta rays can travel through the skin easily. Gamma Rays • The waves arising from the high-frequency end of the electromagnetic spectrum that have no mass are known as gamma rays. • They hold the highest power of penetration. • They are the most penetrating but least ionizing and very difficult to resist from entering the body. • The Gamma rays carry a large amount of energy and can also travel via thick concrete and thin lead sheet (less than 2 feet in width).