Important Chemistry and Biology Questions

VIGYAN

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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

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

(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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