The modern periodic table is based on the periodic law proposed by:
A. Henry Moseley
B. John Dalton
C. Dmitri Mendeleev
D. Niels Bohr
Answer: Option A
Solution (By JKSSB Mock Tests)
Henry Moseley discovered that the atomic number (number of protons) is the fundamental property of an element, not atomic mass. He proposed the modern periodic law: properties are periodic functions of atomic numbers. Mendeleev's law was based on atomic mass, which had anomalies.
Explanation:
Charles' law: V ∝ T (Kelvin) at constant P and n. V/T = constant. This means if temperature is doubled (in Kelvin), volume doubles. Temperature must be in Kelvin (K = °C + 273). Graph of V vs T is a straight line passing through origin. This law is used in hot air balloons: heated air expands, decreasing density, providing lift. Combined with Boyle's law gives PV = nRT.
Explanation:
Ionic compounds consist of positive and negative ions held together by strong electrostatic forces of attraction (ionic bonds). A large amount of energy is required to overcome these forces, resulting in high melting and boiling points. They also conduct electricity when molten or in solution.
Explanation:
Gamma rays (γ) are high-energy electromagnetic radiation (photons). Unlike alpha particles (mass, +2 charge) and beta particles (mass, -1 charge), gamma rays have zero rest mass and no electrical charge. Thus, they are not deflected by electric or magnetic fields.
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