3 public questions tagged with this topic.
C (group 14, valence 4) and Cl (group 17, valence 1) form CCl₄ by sharing electrons to achieve stable configurations.
Ref: NCERT Class 11 Chemistry > Chapter 3: Classification of Elements and Periodicity in Properties > Topic: Modern Periodic Law and Present Form - Long Form Periodic Table
Beer-Lambert law integrates Lambert observation that absorbance proportional to path length and Beer observation proportional to concentration. Resulting expression equates absorbance to product of molar absorptivity ε reflecting transition probability, molar concentration c and path length l in centimeters. Mathematically A = log10(I0/I) = ε c l, valid under dilute, non-scattering, monochromatic light conditions. Deviation occurs at high concentration, polychromatic radiation or scattering. This fundamental equation underlies spectrophotometric determination of proteins, nucleic acids, NADH kinetics, enzyme assays, equilibrium constant measurement, essential for NEET, CBSE and CSIR-NET quantitative problem solving.
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.
Net primary productivity is the rate at which producers accumulate new organic matter after meeting their own respiratory costs. Gross primary productivity represents all carbon fixed or energy captured by autotrophs. Autotrophic respiration consumes part of that material to support cellular maintenance, active transport, tissue construction, and repair. The balance is therefore NPP = GPP − R, where R in this formula means respiration by primary producers, often written Ra. NPP supplies plant growth and reproduction and is the energy potentially available to herbivores and decomposers. Adding respiration would count respired carbon as retained production, while reversing the subtraction could yield a biologically meaningless negative value. Division by respiration is a ratio, not a production rate. This equation must also be distinguished from net ecosystem production, which subtracts both autotrophic and heterotrophic respiration from GPP. The carbon-balance mechanism explains the sign: photosynthesis adds organic carbon to producer biomass, whereas respiration oxidizes some organic carbon and returns carbon dioxide, leaving the difference as net production.
Ref: Ecology: From Individuals to Ecosystems, Begon et al., 5th Ed., Ch. 17
