The half-life of a radioactive isotope is 10 days. What fraction of the original sample remains after 30 days? MCQ with Answer and Explanation

Explanation:
According to the law of conservation of mass, the mass of a substance remains constant during any physical change, including the interconversion of states. Density, volume, and shape change as the intermolecular spaces and arrangement alter during phase transitions, but the total number of atoms and mass is conserved.

Explanation:
Solder is an alloy primarily used for welding electrical components and pipes. It is traditionally composed of lead (Pb) and tin (Sn), typically in a 60:40 or 50:50 ratio. Brass is copper and zinc, bronze is copper and tin, and duralumin is an alloy of aluminum, copper, magnesium, and manganese.

Explanation:
A buffer solution maintains a relatively constant pH when small amounts of strong acid or base are added. However, it is typically composed of a weak acid and its conjugate base (or a weak base and its conjugate acid). A strong acid completely dissociates and cannot form a buffer system. Thus, only statement 1 is correct.