The NEET (National Eligibility cum Entrance Test) is a highly competitive exam that students take to pursue a career in medicine and healthcare. Chemistry is an essential subject for NEET, and having a good conceptual understanding is crucial to achieving a high score. To assist students in preparing for the NEET Chemistry section, a collection of the top 50 conceptual questions has been compiled, covering various topics such as organic chemistry, inorganic chemistry, physical chemistry, and more. These questions are designed to assess a student's understanding of fundamental concepts and their ability to apply them to real-world situations. Practicing these questions can help students develop their problem-solving abilities and perform well on the NEET Chemistry section.
1. What is the molecular formula of glucose?
Ans: The molecular formula of glucose is C6H12O6.
2. Define Avogadro's number and its significance.
Ans: Avogadro's number is the number of particles (atoms, molecules, or ions) in one mole of a substance, which is approximately 6.022 x 10^23. It is significant because it allows chemists to easily convert between mass and number of particles in a substance, and to calculate the stoichiometry of chemical reactions.
3. What is the pH of a solution with a hydrogen ion concentration of 1 x 10^-8 M?
Ans: The pH of a solution with a hydrogen ion concentration of 1 x 10^-8 M is 8.
4. What is the molecular formula of acetic acid?
Ans: The molecular formula of acetic acid is CH3COOH.
5. Explain the difference between an acid and a base.
Ans: Acids are substances that donate hydrogen ions (H+) in a solution, while bases are substances that accept H+ ions or donate hydroxide ions (OH-) in a solution. Acids have a pH less than 7, while bases have a pH greater than 7.
6. What is the molecular formula of methane?
Ans: The molecular formula of methane is CH4.
7. What is the ideal gas law equation?
Ans: The ideal gas law equation is PV=nRT, where P is pressure, V is volume, n is the number of moles of gas, R is the gas constant, and T is temperature.
8. Define Hess's law and explain how it is used to calculate the enthalpy of a reaction.
Ans: Hess's law states that the enthalpy change of a reaction is independent of the pathway taken, and is only dependent on the initial and final states of the reactants and products.
This law can be used to calculate the enthalpy change of a reaction by combining the enthalpy changes of a series of reactions that add up to the overall reaction.
9. What is the function of a catalyst in a chemical reaction?
Ans: A catalyst is a substance that increases the rate of a chemical reaction without being consumed in the reaction itself. It works by lowering the activation energy required for the reaction to occur.
10. What is the chemical formula of sodium chloride?
Ans: The chemical formula of sodium chloride is NaCl.
11. What is the difference between an ionic bond and a covalent bond?
Ans: An ionic bond is formed when electrons are transferred from one atom to another, resulting in positively and negatively charged ions that are attracted to each other. A covalent bond is formed when atoms share electrons to achieve a stable electron configuration.
12. What is the difference between a physical change and a chemical change?
Ans: A physical change is a change in a substance's physical properties, such as shape, size, or phase, without changing its chemical composition. A chemical change is a change in a substance's chemical composition, resulting in the formation of new substances with different properties.
13. What is the molecular formula of sulfuric acid?
Ans: The molecular formula of sulfuric acid is H2SO4.
14. Define oxidation and reduction.
Ans: Oxidation is the loss of electrons by a substance, while reduction is the gain of electrons by a substance. These processes always occur together in a redox reaction.
15. What is the chemical formula of water?
Ans: The chemical formula of water is H2O.
16. What is the difference between an exothermic and endothermic reaction?
Ans: An exothermic reaction releases heat to the surroundings, while an endothermic reaction absorbs heat from the surroundings.
17. What is the molecular formula of ethanol?
Ans: The molecular formula of ethanol is C2H5OH.
18. Define stoichiometry and explain how it is used to calculate the amount of reactants and products in a chemical reaction.
Ans: Stoichiometry is the calculation of the amounts of reactants and products in a chemical reaction based on the balanced chemical equation. It is used to determine the amount of one substance required to react with a certain amount of another substance, or the amount of product that will be produced from a given amount of reactants.
19. What is the molecular formula of ethane?
Ans: The molecular formula of ethane is C2H6.
20. Explain the difference between a homogeneous and heterogeneous mixture.
Ans: A homogeneous mixture has a uniform composition throughout, while a heterogeneous mixture has different components that can be physically distinguished from each other.
21. What is the molecular formula of aspirin?
Ans: The molecular formula of aspirin is C9H8O4.
22. Define molarity and explain how it is used to calculate the concentration of a solution.
Ans: Molarity is a measure of the concentration of a solution, defined as the number of moles of solute per liter of solution. It is used to calculate the amount of solute required to make a solution of a certain concentration, or to calculate the volume of solution required to contain a certain amount of solute.
23. What is the molecular formula of butane?
Ans: The molecular formula of butane is C4H10.
24. What is the difference between a polar and nonpolar molecule?
Ans: A polar molecule has a partial positive and partial negative charge due to the unequal sharing of electrons in a covalent bond, while a nonpolar molecule has no partial charges and the electrons are shared equally.
25. What is the molecular formula of propane?
Ans: The molecular formula of propane is C3H8.
26. What is the molecular formula of nitric acid?
Ans: The molecular formula of nitric acid is HNO3.
27. Define entropy and explain how it relates to the spontaneity of a reaction.
Ans: Entropy is a measure of the disorder or randomness of a system. In a spontaneous reaction, the entropy of the system increases, meaning that there is a greater degree of disorder. This is related to the second law of thermodynamics, which states that the entropy of the universe always increases.
28. What is the molecular formula of hydrochloric acid?
Ans: The molecular formula of hydrochloric acid is HCl.
29. . What is the difference between a reversible and irreversible reaction?
Ans: A reversible reaction can proceed in both the forward and reverse directions, while an irreversible reaction proceeds only in the forward direction. Reversible reactions reach a state of equilibrium where the rates of the forward and reverse reactions are equal.
30. What is the molecular formula of carbon dioxide?
Ans: The molecular formula of carbon dioxide is CO2.
31. Define a Lewis acid and a Lewis base.
Ans: A Lewis acid is a substance that accepts a pair of electrons during a chemical reaction, while a Lewis base is a substance that donates a pair of electrons during a chemical reaction.
32. What is the molecular formula of benzene?
Ans: The molecular formula of benzene is C6H6.
33. Define electronegativity and explain how it relates to the polarity of a molecule.
Ans: Electronegativity is a measure of an atom's ability to attract electrons towards itself in a covalent bond. It relates to the polarity of a molecule because if two atoms in a bond have different electronegativities, the bond will be polar and the electron density will be shifted towards the more electronegative atom.
34. What is the molecular formula of ammonia?
Ans: The molecular formula of ammonia is NH3.
35. Define a buffer solution and explain how it works.
Ans: A buffer solution is a solution that resists changes in pH when small amounts of acid or base are added to it. It works by containing a weak acid and its conjugate base, or a weak base and its conjugate acid, which can neutralize small amounts of added acid or base without changing the pH of the solution significantly.
36. What is the molecular formula of phosphoric acid?
Ans: The molecular formula of phosphoric acid is H3PO4.
37. Define a transition metal and explain their properties.
Ans: Transition metals are elements in the d-block of the periodic table, which are characterized by their partially filled d orbitals. They have unique properties such as the ability to form complex ions and compounds, variable oxidation states, and the ability to catalyze reactions.
38. What is the molecular formula of sodium hydroxide?
Ans: The molecular formula of sodium hydroxide is NaOH.
39. Explain the difference between a primary, secondary, and tertiary alcohol.
Ans: Primary, secondary, and tertiary alcohols refer to the number of carbon atoms attached to the carbon atom with the hydroxyl (-OH) group. A primary alcohol has one carbon attached, a secondary alcohol has two carbons attached, and a tertiary alcohol has three carbons attached.
40. What is the molecular formula of butanol?
Ans: The molecular formula of butanol is C4H9OH.
41. Define chirality and explain how it relates to stereoisomers.
Ans: Chirality is a property of a molecule that is not superimposable on its mirror image. Stereoisomers are molecules that have the same chemical formula and connectivity but differ in the three-dimensional arrangement of their atoms in space. Chiral molecules have stereoisomers that are mirror images of each other, called enantiomers.
42. What is the molecular formula of acetylene?
Ans: The molecular formula of acetylene is C2H2.
43. Define the Henderson-Hasselbalch equation and explain how it is used to calculate the pH of a buffer solution.
Ans: The Henderson-Hasselbalch equation is a mathematical equation that relates the pH of a buffer solution to the pKa of the weak acid and the ratio of its conjugate base to acid. It is used to calculate the pH of a buffer solution by manipulating the equation to solve for pH.
44. What is the molecular formula of sulfur dioxide?
Ans: The molecular formula of sulfur dioxide is SO2.
45. Define intermolecular forces and explain how they relate to the physical properties of substances.
Ans: Intermolecular forces are the attractive or repulsive forces between molecules that determine their physical properties such as boiling point, melting point, and viscosity. The three main types of intermolecular forces are London dispersion forces, dipole-dipole forces, and hydrogen bonding.
46. What is the molecular formula of nitrous oxide?
Ans: The molecular formula of nitrous oxide is N2O.
47. Define a halogen and explain their properties.
Ans: A halogen is a group of elements in the periodic table that includes fluorine, chlorine, bromine, iodine, and astatine. They are highly reactive nonmetals that readily form salts with metals, and are used in a variety of applications such as disinfectants, pesticides, and refrigerants.
48. What is the molecular formula of potassium permanganate?
Ans: The molecular formula of potassium permanganate is KMnO4.
49. Explain the difference between a strong and weak acid.
Ans: The difference between a strong and weak acid lies in their ability to dissociate completely in water. A strong acid dissociates completely in water, whereas a weak acid only partially dissociates. This means that strong acids have a higher concentration of hydrogen ions and are more acidic than weak acids.
50. What is the molecular formula of magnesium oxide?
Ans: The molecular formula of magnesium oxide is MgO.