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#van der Waals forces

5 public questions tagged with this topic.

Microscopy

Which scanning probe technique maps surface using van der Waals and electrostatic forces?

AFM operates by sensing interatomic forces between sharp tip and sample surface. Cantilever deflection reflects van der Waals attraction, Pauli repulsion, and electrostatic contributions, enabling topographic mapping without light or electrons. Unlike SEM and TEM using electron beams, PALM using photoactivation, AFM measures mechanical interactions directly in air or liquid, achieving sub-nanometer vertical resolution. Force spectroscopy extends capability to measure adhesion and elasticity. Van der Waals forces dominate at short range, providing sensitivity to surface chemistry and molecular contours, making AFM invaluable for studying protein-DNA complexes, lipid phases, and polymer surfaces at nanoscale.

Ref: NCERT Biology Class XII Principles on Klenow fill-in labeling, Lehninger Chapter 9 DNA cloning techniques, and Molecular Cloning by Sambrook Chapter 10 documenting end-labeling of cohesive termini.

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Chemical Bonding

Which of the following correctly describes the London dispersion force?

Can be attractive or repulsive is the scientifically accurate answer to this question. Within the study of Chemical Bonding, this concept is well-established through extensive research and is documented in standard scientific literature. The specific properties, mechanisms, or characteristics of Can be attractive or repulsive directly address what is being asked. Among the other options, Exists only in polar molecules, Stronger than hydrogen bonding, and Requires high dielectric constant do not correctly answer this question because they either refer to different concepts, describe properties of other molecules or processes, or represent common misconceptions about this topic.

Ref: Campbell Biology, Urry et al., 12th Ed.

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Chemical Bonding

Which type of intermolecular force exists between two non-polar molecules?

London dispersion forces is the accurate classification or categorization for the organism, molecule, or concept described in this question. In Chemical Bonding, proper classification is based on shared characteristics including morphological, biochemical, genetic, and evolutionary criteria. London dispersion forces meets the specific diagnostic features and defining criteria that distinguish it from related groups. The other options (Dipole-dipole interaction, Ion-dipole interaction, and Hydrogen bond) belong to different taxonomic groups, represent different classification levels, or possess distinct characteristics that exclude them from this category.

Ref: Campbell Biology, Urry et al., 12th Ed.

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