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91
Chemistry Medium

Which process involves passing an electric current through a solution to cause a chemical reaction?

  • AElectrolysis
  • BDistillation
  • CChromatography
  • DFiltration
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Correct Answer: Option A — Electrolysis
Explanation: Electrolysis passes an electric current through an electrolyte solution or molten ionic compound causing chemical reactions at the electrodes and is used to extract metals and plate surfaces.
Submitted by: PaperMCQs
92
Chemistry Medium

Which element is essential for the structure of DNA and RNA molecules alongside carbon hydrogen oxygen and nitrogen?

  • ASulfur
  • BCalcium
  • CIron
  • DPhosphorus
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Correct Answer: Option D — Phosphorus
Explanation: Phosphorus is a key element in DNA and RNA molecules forming the phosphate backbone of the double helix structure and is also essential in ATP the cell's energy currency.
Submitted by: PaperMCQs
93
Chemistry Medium

Which chemical process is used to extract metals from their ores using carbon or electrolysis?

  • AReduction
  • BOxidation
  • CNeutralisation
  • DChromatography
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Correct Answer: Option A — Reduction
Explanation: Reduction is used to extract metals from their ores by removing oxygen using a reducing agent like carbon or by electrolysis for more reactive metals like aluminium.
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94
Chemistry Medium

Which type of chemical bond exists between water molecules causing its unusually high boiling point?

  • ACovalent bond
  • BHydrogen bond
  • CIonic bond
  • DVan der Waals force
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Correct Answer: Option B — Hydrogen bond
Explanation: Hydrogen bonds between water molecules are responsible for water's unusually high boiling point surface tension and many other unique properties essential for life.
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95
Chemistry Medium

Which isotope of carbon is used in radiocarbon dating?

  • ACarbon-12
  • BCarbon-13
  • CCarbon-11
  • DCarbon-14
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Correct Answer: Option D — Carbon-14
Explanation: Carbon-14 is a radioactive isotope used in radiocarbon dating of organic materials because it decays at a known rate allowing scientists to estimate the age of ancient samples.
Submitted by: PaperMCQs
96
Chemistry Medium

What is an isotope?

  • AAtoms of different elements with the same mass
  • BAtoms of the same element with different numbers of protons
  • CAtoms of the same element with the same number of protons but different neutrons
  • DAtoms of different elements with the same electrons
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Correct Answer: Option C — Atoms of the same element with the same number of protons but different neutrons
Explanation: Isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons resulting in different mass numbers but similar chemical properties.
Submitted by: PaperMCQs
97
Chemistry Hard

Which element has the highest electronegativity on the Pauling scale?

  • AOxygen
  • BChlorine
  • CNitrogen
  • DFluorine
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Correct Answer: Option D — Fluorine
Explanation: Fluorine has the highest electronegativity of all elements at 3.98 on the Pauling scale due to its small atomic size and high effective nuclear charge on its outer electrons.
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98
Physics Medium

Which instrument is used to detect and measure very small electric currents?

  • AVoltmeter
  • BOhmmeter
  • CAmmeter
  • DGalvanometer
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Correct Answer: Option D — Galvanometer
Explanation: A galvanometer is a sensitive instrument used to detect and measure very small electric currents through the deflection of a needle in a magnetic field.
Submitted by: PaperMCQs
99
Physics Hard

Which fundamental force is responsible for radioactive beta decay?

  • AGravitational force
  • BElectromagnetic force
  • CStrong nuclear force
  • DWeak nuclear force
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Correct Answer: Option D — Weak nuclear force
Explanation: The weak nuclear force is responsible for radioactive beta decay where a neutron transforms into a proton by emitting an electron and an antineutrino.
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100
Physics Hard

What is the name of the force that holds protons and neutrons together inside the nucleus?

  • AElectromagnetic force
  • BGravitational force
  • CStrong nuclear force
  • DWeak nuclear force
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Correct Answer: Option C — Strong nuclear force
Explanation: The strong nuclear force holds protons and neutrons together inside the atomic nucleus and is the strongest of the four fundamental forces operating only at very short ranges.
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