Two miscible liquids with a boiling point difference of less than 25 K can be separated by:
A. Crystallization
B. Simple distillation
C. Fractional distillation
D. Separating funnel
Answer: Option C
Solution (By JKSSB Mock Tests)
Fractional distillation is used when the boiling points differ by less than 25 K. A fractionating column provides repeated condensation–vaporization cycles, improving separation. Example: separation of petrol, kerosene from crude oil. Simple distillation works if difference > 25 K. Separating funnel separates immiscible liquids. Crystallization purifies solids. Exam note: Fractionating column packed with glass beads increases surface area.
Explanation:
Atomic number (Z) is the number of protons in the nucleus, which defines the identity of the element. In a neutral atom, the number of electrons equals Z. Neutrons contribute to mass number but not atomic number. Isotopes have same Z but different number of neutrons. Nucleons are total protons + neutrons = mass number. The modern periodic table is based on atomic number.
Explanation:
John Dalton formulated the law of multiple proportions: If two elements can combine to form more than one compound, the masses of one element that combine with a fixed mass of the other are in ratios of small whole numbers. Lavoisier gave law of conservation of mass. Proust gave law of definite proportions. Dalton's atomic theory explained these laws.
Explanation:
Zn + H₂SO₄ → ZnSO₄ + H₂↑. Hydrogen gas is released, which burns with a pop sound. This is a test for hydrogen. Metals above hydrogen in reactivity series displace it from acids. Dilute H₂SO₄ with Zn produces H₂; with Cu, no reaction.
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