NEET doubts
500 doubts found
What is the difference between system and surroundings?
The system is the reaction you study; the surroundings are everything else that can exchange heat/work with it.
What is the difference between adding heat to exothermic and adding heat to endothermic?
Heating an exothermic reaction shifts it backward (toward reactants); heating an endothermic one shifts it forward (toward products).
How do I revise Redox Reactions quickly before the exam?
One-page summary of Oxidation and reduction, Oxidation number, Oxidising and reducing agents, then timed previous-year questions.
What is the difference between group and period?
A group is a vertical column (same valence electrons, similar properties); a period is a horizontal row (same number of shells).
What is the difference between catalyst on rate and catalyst on equilibrium?
A catalyst speeds a reaction by lowering activation energy but does NOT shift the equilibrium position.
When do I use E_cell = E_cathode − E_anode in Electrochemistry, and what does it mean?
standard cell EMF from electrode potentials.
What is the difference between SN1 reaction and SN2 reaction?
SN1 goes through a carbocation in two steps (favoured by 3° substrates); SN2 is a one-step backside attack (favoured by 1° substrates).
What are the most common mistakes students make in Hydrocarbons?
H adds to the carbon with more hydrogens — unless peroxides are present, which reverse it (anti-Markovnikov).
When do I use n = mass / molar mass in Some Basic Concepts (Mole Concept), and what does it mean?
number of moles from a given mass.
When do I use E_n = −13.6 Z²/n² eV in Structure of Atom, and what does it mean?
energy of an electron in a hydrogen-like atom.
What is the difference between sigma bond and pi bond?
A sigma bond forms by head-on overlap and is strong; a pi bond forms by sideways overlap of p-orbitals and is weaker.
When do I use ΔG = ΔH − TΔS in Chemical Thermodynamics, and what does it mean?
Gibbs free energy change deciding spontaneity.
When do I use pH = −log[H⁺] in Equilibrium, and what does it mean?
acidity of a solution.
What does “Cell theory” actually mean in Cell: The Unit of Life, and why does it matter for NEET?
all living organisms are made of cells, and every cell arises from a pre-existing cell.
What does “Enzymes” actually mean in Biomolecules, and why does it matter for NEET?
biological catalysts (mostly proteins) that speed reactions by lowering activation energy.
What does “Phases of the cell cycle” actually mean in Cell Cycle & Cell Division, and why does it matter for NEET?
G1 (growth), S (DNA replication), G2 (growth) make up interphase, followed by M phase (division).
What does “Light reactions” actually mean in Photosynthesis in Higher Plants, and why does it matter for NEET?
occur in the thylakoid membranes, using light to make ATP and NADPH and releasing O₂ by splitting water.
What does “Glycolysis” actually mean in Respiration in Plants, and why does it matter for NEET?
the splitting of glucose into two pyruvate molecules in the cytoplasm, giving a net of 2 ATP.
What does “Digestive enzymes” actually mean in Digestion & Absorption, and why does it matter for NEET?
amylase breaks starch, pepsin and trypsin break proteins, and lipase breaks fats — each in its own region.
What does “Gas exchange” actually mean in Breathing & Exchange of Gases, and why does it matter for NEET?
oxygen and carbon dioxide swap by diffusion across the thin, moist walls of the alveoli.
What does “Double circulation” actually mean in Body Fluids & Circulation, and why does it matter for NEET?
blood passes through the heart twice in one complete circuit — once to the lungs, once to the body.
What does “Nephron” actually mean in Excretory Products & Elimination, and why does it matter for NEET?
the microscopic filtering unit of the kidney where urine formation begins.
What does “Neuron” actually mean in Neural Control & Coordination, and why does it matter for NEET?
the nerve cell that carries impulses, with dendrites (receive), an axon (transmit) and synapses (connect).
What does “Hormones” actually mean in Chemical Coordination (Endocrine System), and why does it matter for NEET?
chemical messengers released by ductless (endocrine) glands into the blood to act on target organs.