Chapter 1: Periodic Classification of Elements
Q1. What is the periodic table? A1. The periodic table is a systematic arrangement of elements in order of their atomic numbers, showing periodic repetition of properties.
Q2. What is the modern periodic law? A2. The modern periodic law states that the physical and chemical properties of elements are periodic functions of their atomic numbers.
Q3. How many periods are there in the modern periodic table? A3. There are 7 periods in the modern periodic table.
Q4. How many groups are there in the modern periodic table? A4. There are 18 groups in the modern periodic table.
Q5. What happens to atomic size as we move down a group? A5. Atomic size increases as we move down a group due to the addition of new electron shells.
Q6. What happens to atomic size as we move across a period? A6. Atomic size decreases as we move across a period due to increasing nuclear charge.
Q7. What is ionisation energy? A7. Ionisation energy is the minimum energy required to remove an electron from an isolated gaseous atom.
Q8. How does ionisation energy vary in the periodic table? A8. Ionisation energy increases across a period and decreases down a group.
Q9. What is electronegativity? A9. Electronegativity is the tendency of an atom to attract electrons towards itself in a chemical bond.
Q10. Which element has the highest electronegativity? A10. Fluorine has the highest electronegativity value of 4.0.
Chapter 2: Chemical Bonding
Q11. What is a chemical bond? A11. A chemical bond is the force of attraction that holds atoms together in a molecule or compound.
Q12. What are the main types of chemical bonds? A12. The main types are:
- Ionic bonds (electrovalent bonds)
- Covalent bonds
- Metallic bonds
Q13. What is an ionic bond? A13. An ionic bond is formed by the complete transfer of electrons from a metal atom to a non-metal atom, resulting in the formation of ions.
Q14. What is a covalent bond? A14. A covalent bond is formed by the sharing of electrons between atoms.
Q15. What is the octet rule? A15. The octet rule states that atoms tend to gain, lose, or share electrons to achieve a stable configuration of 8 electrons in their outermost shell.
Q16. Give an example of ionic compound formation. A16. NaCl formation: Na → Na⁺ + e⁻ and Cl + e⁻ → Cl⁻, then Na⁺ + Cl⁻ → NaCl
Q17. What are the properties of ionic compounds? A17. Properties of ionic compounds:
- High melting and boiling points
- Conduct electricity in molten state or solution
- Soluble in polar solvents like water
- Hard and brittle
Q18. What are the properties of covalent compounds? A18. Properties of covalent compounds:
- Low melting and boiling points
- Do not conduct electricity
- Soluble in non-polar solvents
- Soft
Chapter 3: Acids, Bases and Salts
Q19. What are acids according to Arrhenius theory? A19. According to Arrhenius theory, acids are substances that produce H⁺ ions in aqueous solution.
Q20. What are bases according to Arrhenius theory? A20. Bases are substances that produce OH⁻ ions in aqueous solution.
Q21. What is the pH scale? A21. The pH scale is a measure of hydrogen ion concentration in a solution, ranging from 0 to 14.
Q22. What is the pH of pure water? A22. The pH of pure water is 7 (neutral).
Q23. What are indicators? A23. Indicators are substances that change color in acidic or basic solutions. Examples: litmus paper, methyl orange, phenolphthalein.
Q24. What happens when acids react with metals? A24. Acids react with metals to produce hydrogen gas and a salt. Example: Zn + H₂SO₄ → ZnSO₄ + H₂
Q25. What happens when acids react with carbonates? A25. Acids react with carbonates to produce carbon dioxide, water, and a salt. Example: CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂
Q26. What is neutralization? A26. Neutralization is the reaction between an acid and a base to form salt and water. Example: HCl + NaOH → NaCl + H₂O
Q27. What are salts? A27. Salts are ionic compounds formed by the reaction between acids and bases.
Q28. Name some common salts and their uses. A28. Common salts and uses:
- NaCl (table salt) - food preservation
- CaCO₃ (limestone) - cement manufacture
- NaHCO₃ (baking soda) - baking, antacid
Chapter 4: Carbon and its Compounds
Q29. Why does carbon form covalent bonds? A29. Carbon forms covalent bonds because it has 4 electrons in its outermost shell and needs 4 more electrons to complete its octet. Sharing electrons is more feasible than gaining or losing 4 electrons.
Q30. What is catenation? A30. Catenation is the ability of carbon atoms to form bonds with other carbon atoms, forming long chains and rings.
Q31. What are hydrocarbons? A31. Hydrocarbons are compounds containing only carbon and hydrogen atoms.
Q32. What are saturated hydrocarbons? A32. Saturated hydrocarbons (alkanes) contain only single bonds between carbon atoms. General formula: CₙH₂ₙ₊₂
Q33. What are unsaturated hydrocarbons? A33. Unsaturated hydrocarbons contain double or triple bonds between carbon atoms:
- Alkenes (double bonds): CₙH₂ₙ
- Alkynes (triple bonds): CₙH₂ₙ₋₂
Q34. What is the difference between addition and substitution reactions? A34.
- Addition reactions: Unsaturated compounds add atoms/groups without losing any atoms
- Substitution reactions: One atom/group is replaced by another atom/group
Q35. What is combustion of hydrocarbons? A35. Combustion is the reaction of hydrocarbons with oxygen to produce carbon dioxide and water, releasing energy. Example: CH₄ + 2O₂ → CO₂ + 2H₂O + energy
Chapter 5: Life Processes - Nutrition
Q36. What is nutrition? A36. Nutrition is the process by which organisms obtain and utilize food for growth, maintenance, and energy.
Q37. What are the two main types of nutrition? A37. The two main types are:
- Autotrophic nutrition (self-feeding)
- Heterotrophic nutrition (dependent on others)
Q38. What is photosynthesis? A38. Photosynthesis is the process by which green plants make their own food using sunlight, carbon dioxide, and water. Equation: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂ (in presence of sunlight and chlorophyll)
Q39. What are the raw materials for photosynthesis? A39. The raw materials are:
- Carbon dioxide (from air)
- Water (from soil)
- Sunlight (energy source)
- Chlorophyll (catalyst)
Q40. What are the products of photosynthesis? A40. The products are:
- Glucose (food)
- Oxygen (released into atmosphere)
Practice Questions for Revision
Q41. Arrange the following in increasing order of atomic size: Na, Mg, Al, Si A41. Si < Al < Mg < Na (atomic size decreases across a period)
Q42. Which has higher ionization energy: Li or F? A42. F has higher ionization energy because it's smaller in size and has higher nuclear charge.
Q43. Write the electron dot structure of water (H₂O). A43. H:Ö:H (oxygen shares one electron each with two hydrogen atoms)
Q44. What type of bond is present in CaCl₂? A44. Ionic bond (Ca²⁺ and Cl⁻ ions are held together by electrostatic forces)
Q45. Why do ionic compounds conduct electricity in molten state? A45. In molten state, ions are free to move and carry electric current.
Q46. What is the molecular formula of methane? A46. CH₄
Q47. Write the structural formula of ethane. A47. H₃C-CH₃
Q48. What happens when ethene reacts with hydrogen? A48. C₂H₄ + H₂ → C₂H₆ (addition reaction to form ethane)
Q49. What is the pH of lemon juice? A49. The pH of lemon juice is around 2 (acidic).
Q50. Name the gas evolved when zinc reacts with hydrochloric acid. A50. Hydrogen gas (H₂) is evolved.
Important Formulas and Equations
Chemical Bonding
- Ionic bond formation: Metal → Metal⁺ + e⁻; Non-metal + e⁻ → Non-metal⁻
- Covalent bond: Sharing of electrons
Acids and Bases
- Neutralization: Acid + Base → Salt + Water
- Metal + Acid → Salt + H₂
- Carbonate + Acid → Salt + H₂O + CO₂
Hydrocarbons
- Alkanes: CₙH₂ₙ₊₂
- Alkenes: CₙH₂ₙ
- Alkynes: CₙH₂ₙ₋₂
- Combustion: Hydrocarbon + O₂ → CO₂ + H₂O + Energy
Photosynthesis
- 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂ (in presence of sunlight and chlorophyll)
Tips for Exam Preparation
- Practice drawing electron dot structures for simple molecules
- Memorize the first 20 elements and their positions in the periodic table
- Learn the properties of ionic and covalent compounds
- Practice balancing chemical equations
- Understand the pH scale and common examples
- Know the structural formulas of first few alkanes, alkenes, and alkynes
- Practice naming organic compounds using IUPAC nomenclature
Remember to solve the question papers from the previous year and practice numerical problems regularly!