Important Chemistry and Biology Questions

Important Chemistry and Biology Questions - PYQs

Question 1:

Mention the type of chemical reaction that takes place and write the chemical equation for each reaction:

• (i) A magnesium ribbon is burnt in air
  
  2Mg(s) + O₂(g) → 2MgO(s): Combination Reaction
• (ii) Limestone is heated
  
  CaCO₃(s) → CaO(s) + CO₂(g): Thermal Decomposition Reaction
• (iii) Silver bromide is exposed to sunlight
  
  2AgBr(s) → 2Ag(s) + Br₂: Photolytic Decomposition Reaction
• (iv) Electricity is passed through acidified water
  
  2H₂O(l) → 2H₂(g) + O₂(g): Electrolytic Decomposition reaction
• (v) Ammonia and hydrogen chloride are mixed
  
  NH₃(g) + HCl(g) → NH₄Cl(s): Combination Reaction

Question 2:

Take 3 g of barium hydroxide in a test tube, add 2 g of ammonium chloride, and mix. Now touch the test tube from outside.

• (i) Observation: The test tube becomes cooler as the reaction absorbs heat from the surroundings.
• (ii) Type of Reaction: Endothermic reaction.
• (iii) Balanced Chemical Equation:
  
  Ba(OH)₂ + 2NH₄Cl + Heat → BaCl₂ + 2NH₃ + 2H₂O

Question 3:

• (a) How is a zygote formed?
  A zygote is formed by the fusion of male and female gametes.
• (b) Function of Placenta:
  The placenta provides nutrition to the developing embryo from the mother's blood and removes embryo waste.
• (c) Egg Formation in Human Females:
  A mature egg is released once in a menstrual cycle (~28 days).
• (d) Two Bacterial STDs:
  Gonorrhoea and Syphilis.
• (e) Why is prenatal sex determination prohibited?
  It is misused, leading to female foeticide.

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