Boyle's law states that at constant temperature, the pressure of a gas is inversely proportional to its: MCQ with Answer and Explanation

Explanation:
Ernest Rutherford, along with his students Geiger and Marsden, conducted the famous gold foil experiment in 1911. By observing that a few alpha particles bounced back, he concluded that the atom has a small, dense, positively charged center called the nucleus.

Explanation:
Cobalt-60 emits high-energy gamma rays used in radiotherapy (teletherapy) to treat cancers by damaging DNA of malignant cells. Carbon-14 is used for radiocarbon dating. Americium-241 is used in smoke detectors. Phosphorus-32 is used as tracer. Radiotherapy must be carefully targeted to minimize damage to healthy tissue.

Explanation:
Mass number (A) = number of protons (Z) + number of neutrons (N). Electrons have negligible mass and are not counted. It is the total number of nucleons. Example: ¹²C has 6 protons + 6 neutrons = 12. Isotopes have same Z but different A due to varying N. Atomic mass (weight) is the weighted average.