Objective

Question-2. Ripening of fruits is an example of which reaction?

Ans- chemical reaction

Question-3. What is an example of formation of ice from water?

Ans- physical reaction

Question-4. What happens when magnesium is burned in the presence of oxygen?

Ans- magnesium oxide

Question-5. What is the colour of magnesium oxide powder?

Ans- White

Question-6. What is the ratio of atomic numbers of hydrogen and oxygen in water?

Ans- 2:1 ( H₂O)

Question-7. How is the balance of oxygen maintained in nature?

Ans- by photosynthesis

Question-8. What does sodium combine with water to form?

Ans- sodium hydroxide and water

Question-9. What is the atomic number of sodium?

Ans- 11

Question-10. What is the chemical formula of marble?

Ans- CaCO₃

Question-11. Which gas is responsible for global warming?

Ans- CO₂

Question-12. Which rule is followed in balancing a chemical equation?

Ans- law of conservation of mass

Question-13. How many methods are there to balance a chemical equation?

Ans- two (approximation method, algebraic method)

Question-14. Nitrogen (N) combines with hydrogen gas (3H₂) to form what?

Ans- ammonia (2NH₃)

Question-15. 2H₂(g) + O₂(g) → 2H₂O(l) is what kind of reaction?

Ans- combination reaction

Question-16. CaCo₃(s) → CaO(s) + CO₂(g) What is the reaction?

Ans- decomposition reaction

Question-17. CH₄ + 2O₂ → CO₂ + 2H₂O + energy (heat) What is the reaction?

Ans- exothermic chemical reaction

Question-18. What is a substance that inhibits oxidation called?

Ans- Antioxidant

Question-19. Which gas is kept in the bag of chips?

Ans- nitrogen

Question-20. What is another name for oxidation-reduction reaction?

Ans- redox

Question-21. What does iron combine with oxygen to form?

Ans- iron oxide (ferrous oxide)

Question-22. What kind of chemical reaction is respiration?

Ans- exothermic reaction (combustion reaction)

Question-23. Is helium a gas element?

Ans- inert

Question-24. What are the electrodes at the negative end of the battery and the electrode connected to the positive end called?

Ans-

electrode attached to the minus end → cathode

electrodes connected to the positive end → anode

Question-25. When an electric current is passed through sodium chloride, what does it decompose to form?

Ans- Na (sodium) metal and Cl₂ (chlorine) gas

Question-26. What makes silver chloride (AgCl) in sunlight?

Ans- silver metal

Question-27. What is the decomposition reaction of silver bromide (AgBr) used for?

Ans- in black and white photography

Question-28. What is the process of digestion of food in the body?

Ans- Decomposition reaction

Question-29. What happens when zinc is added to dilute hydrochloric acid or dilute sulfuric acid?

Ans- formation of hydrogen gas bubbles

Question-30. What happens when quicklime (CaO) is mixed with water?

Ans- slaked lime [Ca(OH)₂] and heat

Question-31. What happens when there is a reaction between lead nitrate [Pb(NO₃)] and potassium iodide (KI)?

Ans- A precipitate is formed and the colour changes.

Question-32. What is formed when barium chloride (BaCl₂) is mixed with dilute sulfuric acid (H₂SO₄)?

Ans- white precipitate of barium sulphate (BaSo4)

Question-33. What are the substances that take part in a chemical reaction called?

Ans- reactant

Question-34. What is the substance formed as a result of a chemical reaction called?

Ans- Product

Question-35. What are the symbols and formulas used in place of words in a chemical equation called?

Ans- chemical equation

Question-36. What is it called when the atomic numbers of the reactants and products are not equal?

Ans- Unbalanced Chemical Equation (Skeleton Equation)

Question-37. What is it called when the atomic numbers of reactants and products are equal?

Ans- balanced chemical equation

Question-38. What is the mass of the reactants and products in a balanced chemical equation?

Ans- same

Question-39. What is a reaction that takes place in the presence of sunlight called?

Ans- photochemical reaction

Question-40. What happens to decomposition reaction, combination reaction?

Ans- Adverse (Opposite)

Question-41. What is the colour of the solution when iron is added to a solution of copper sulphate?

Ans- Green

Question-42. How does the color of the solution change when zinc metal is added to a solution of copper sulphate?

Ans- colorless

Question-43. What is zinc in comparison to copper?

Ans- more reactive

Question-44. What is copper than silver?

Ans- more reactive

Question-45. What is the reaction of ZN(s) + CuSO₄ (aq) → ZNSO₄ (aq) + Cu (s)?

Ans- single displacement reaction

Question-46. Na₂So₄ + BaCl₂ → BaSo₄ + 2NaCl, What is the reaction?

Ans- double displacement reaction

Question-47. What is the reaction AgNo₃ + NaCl → AgCl + NaNO?

Ans- precipitation reaction

Question-48. When a double displacement reaction occurs between an acid and a base, what is it called?

Ans- neutralization reaction

Question-49. HCl + NaOH → NaCl + H₂O What is the reaction?

Ans- neutralization reaction

Question-50. What are the chemical reactions in which energy (heat) is absorbed called?

Ans- endothermic reaction

Question-51. What is the chemical formula of marble?

Ans- calcium carbonate (CaCO₃)

Question-52. What is used for whitewashing the walls?

Ans- slaked lime [Ca(OH)₂]

Question-53. What is the reaction of respiration?

Ans- exothermic reaction

Question-54. What happens when carbohydrates are broken down?

Ans- glucose

Question-55. When a decomposition reaction is carried out by heat, what is it called?

Ans- thermal decomposition

Question-56. What is the color of the solution formed as a result of the neutralization reaction?

Ans- colorless

Question-57. Which reaction is called an oxidation reaction?

Ans- oxidation reaction

Question-58. Which reaction is called reduction reaction?

Ans- reduction reaction

Question-59. What is the reason for which the process of oxidation takes place?

Ans- oxidising

Question-60. What is the name of the process that causes reduction?

Ans- reducing

Question-61. What is combined oxidation and reduction reaction called?

Ans- redox reaction

Question-62. CuO + H₂ → Cu + H₂O

Ans-

anabolic substances → H₂

reduced substance → CuO

Question-63. What is the process of deposition of metals called?

Ans- corrosion

Question-64. Which chemical reaction is used in photography?

Ans- photochemical

Question-65. Reduction is a reaction in which the ratio of oxygen to

Ans- reduces

Question-66. What is the reaction called when magnesium wire is burnt in air?

Ans- combination reaction

Question-67. Lead + Copper Chloride → Lead Chloride + Copper Write the balanced chemical equation of?

Ans- pb + CuCl₂ → pbCl₂ + Cu

Question-68. What is formed by the breakdown of carbohydrates located in food?

Ans- Glucose (C₆H₁₂O₆)

Question-69. What color is the rust coating on iron?

Ans- brown

Question-70. What is the color of copper plated coating due to corrosion?

Ans- green

Question-71. What is the color of silver plated due to corrosion?

Ans- black

Question-72. Which is more active in calcium and zinc?

Ans- Calcium (Ca)

Question-73. When an electric current is passed through an aqueous solution of sodium chloride, it dissociates to form sodium hydroxide. What is this process called?

Ans- chlor-base reaction

Question-74. What is the chemical formula of sugar?

Ans- C₁₂H₂₂O₁₁

Question-75. What is the chemical formula of sodium carbonate?

Ans- Na₂Co₃

Question-76. What does carbon combine with hydrogen to form?

Ans- hydrocarbons

Question-77. What causes rancidity in food items?

Ans- oxidation

Question-78. What is the process of making curd from milk?

Ans- fermentation