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Class X - Science
Full Syllabus - Top 50 Most Expected MCQs
Board: CBSE NCERT
📝 50 Multiple Choice Questions | ⏱️ 50 Minutes
Board Exam 2026 Preparation Test
📚 Quick Revision Points
- Chemistry: Chemical Reactions, Acids-Bases-Salts, Metals-Non-metals, Carbon Compounds
- Biology: Life Processes, Control & Coordination, Reproduction, Heredity
- Physics: Light (Reflection & Refraction), Human Eye, Electricity, Magnetic Effects
- Environment: Our Environment, Ecosystem, Food chains, Ozone depletion
- Key Formulas: Mirror: 1/f=1/v+1/u | Lens: 1/f=1/v-1/u | Ohm: V=IR | Power: P=VI, P=I²R
Q1.
Which of the following is a combination reaction?
Correct Answer: A) CaO + H₂O → Ca(OH)₂
Combination reaction: two or more substances combine to form single product. Calcium oxide and water combine to form calcium hydroxide.
Combination reaction: two or more substances combine to form single product. Calcium oxide and water combine to form calcium hydroxide.
Q2.
What happens when dilute HCl is added to iron filings?
Correct Answer: B) Hydrogen gas and iron chloride are produced
Fe + 2HCl → FeCl₂ + H₂↑. Displacement reaction where iron displaces hydrogen from hydrochloric acid.
Fe + 2HCl → FeCl₂ + H₂↑. Displacement reaction where iron displaces hydrogen from hydrochloric acid.
Q3.
Respiration is an example of:
Correct Answer: A) Exothermic reaction
Respiration releases energy in the form of heat and ATP, making it an exothermic reaction.
Respiration releases energy in the form of heat and ATP, making it an exothermic reaction.
Q4.
Which gas is produced when Zn reacts with dilute H₂SO₄?
Correct Answer: B) Hydrogen
Zn + H₂SO₄ → ZnSO₄ + H₂↑. Hydrogen gas is liberated.
Zn + H₂SO₄ → ZnSO₄ + H₂↑. Hydrogen gas is liberated.
Q5.
Oxidation is:
Correct Answer: B) Gain of oxygen
Oxidation is defined as gain of oxygen, loss of hydrogen, or loss of electrons.
Oxidation is defined as gain of oxygen, loss of hydrogen, or loss of electrons.
Q6.
CaCO₃ → CaO + CO₂ is a:
Correct Answer: B) Decomposition reaction
Thermal decomposition: single compound breaks into two or more products on heating.
Thermal decomposition: single compound breaks into two or more products on heating.
Q7.
Rancidity can be prevented by:
Correct Answer: D) All of the above
All methods prevent oxidation of fats and oils, thus preventing rancidity.
All methods prevent oxidation of fats and oils, thus preventing rancidity.
Q8.
The brown coating on copper vessels is:
Correct Answer: B) Basic copper carbonate
CuCO₃·Cu(OH)₂ forms from reaction with moist air containing CO₂.
CuCO₃·Cu(OH)₂ forms from reaction with moist air containing CO₂.
Q9.
pH of pure water is:
Correct Answer: B) 7
Pure water has pH 7 (neutral). pH < 7 is acidic, pH > 7 is basic.
Pure water has pH 7 (neutral). pH < 7 is acidic, pH > 7 is basic.
Q10.
Which is used for whitewashing walls?
Correct Answer: B) Ca(OH)₂
Calcium hydroxide (slaked lime) reacts with CO₂ in air to form CaCO₃ which gives shiny finish.
Calcium hydroxide (slaked lime) reacts with CO₂ in air to form CaCO₃ which gives shiny finish.
Q11.
Chemical name of baking soda:
Correct Answer: B) Sodium bicarbonate
NaHCO₃ (Sodium bicarbonate) - used in baking and as antacid.
NaHCO₃ (Sodium bicarbonate) - used in baking and as antacid.
Q12.
Which acid is present in vinegar?
Correct Answer: A) Acetic acid
Vinegar contains 5-8% acetic acid (CH₃COOH).
Vinegar contains 5-8% acetic acid (CH₃COOH).
Q13.
Plaster of Paris formula:
Correct Answer: B) CaSO₄·½H₂O
Calcium sulphate hemihydrate - used for casts and moulds.
Calcium sulphate hemihydrate - used for casts and moulds.
Q14.
Tooth enamel is made of:
Correct Answer: A) Calcium phosphate
Hardest substance in body, corroded by acids when pH < 5.5.
Hardest substance in body, corroded by acids when pH < 5.5.
Q15.
Washing soda formula:
Correct Answer: B) Na₂CO₃·10H₂O
Sodium carbonate decahydrate - used for cleaning and softening hard water.
Sodium carbonate decahydrate - used for cleaning and softening hard water.
Q16.
Bleaching powder formula:
Correct Answer: A) CaOCl₂
Calcium oxychloride - used for disinfecting water.
Calcium oxychloride - used for disinfecting water.
Q17.
Best conductor of electricity:
Correct Answer: A) Silver
Silver is best conductor, but copper is commonly used due to cost-effectiveness.
Silver is best conductor, but copper is commonly used due to cost-effectiveness.
Q18.
Metal that does not react with water or acids:
Correct Answer: C) Gold
Gold is a noble metal and least reactive.
Gold is a noble metal and least reactive.
Q19.
Coating iron with zinc is called:
Correct Answer: B) Galvanization
Galvanization protects iron from rusting by zinc coating.
Galvanization protects iron from rusting by zinc coating.
Q20.
Most reactive metal:
Correct Answer: B) Potassium
Potassium is most reactive in reactivity series.
Potassium is most reactive in reactivity series.
Q21.
Alloy of copper and zinc:
Correct Answer: B) Brass
Brass = Copper (Cu) + Zinc (Zn).
Brass = Copper (Cu) + Zinc (Zn).
Q22.
Alloy of copper and tin:
Correct Answer: A) Bronze
Bronze = Copper (Cu) + Tin (Sn).
Bronze = Copper (Cu) + Tin (Sn).
Q23.
Functional group in ethanol:
Correct Answer: B) -OH
Hydroxyl group (-OH) characterizes alcohols like ethanol.
Hydroxyl group (-OH) characterizes alcohols like ethanol.
Q24.
Functional group in ethanoic acid:
Correct Answer: A) -COOH
Carboxyl group (-COOH) characterizes carboxylic acids.
Carboxyl group (-COOH) characterizes carboxylic acids.
Q25.
Number of bonds carbon can form:
Correct Answer: C) 4
Carbon has 4 valence electrons, forms 4 covalent bonds.
Carbon has 4 valence electrons, forms 4 covalent bonds.
Q26.
Saturated hydrocarbons are called:
Correct Answer: C) Alkanes
Alkanes have only single bonds (CₙH₂ₙ₊₂).
Alkanes have only single bonds (CₙH₂ₙ₊₂).
Q27.
Soap is a:
Correct Answer: A) Sodium/potassium salt of fatty acids
Saponification produces soap (salt of fatty acid).
Saponification produces soap (salt of fatty acid).
Q28.
Catenation is maximum in:
Correct Answer: A) Carbon
Carbon has unique ability to form long chains.
Carbon has unique ability to form long chains.
Q29.
Process by which plants make food:
Correct Answer: A) Photosynthesis
6CO₂ + 6H₂O + light → C₆H₁₂O₆ + 6O₂ (chlorophyll needed)
6CO₂ + 6H₂O + light → C₆H₁₂O₆ + 6O₂ (chlorophyll needed)
Q30.
Stomata are present in:
Correct Answer: B) Leaves
Stomata on leaves allow gas exchange and transpiration.
Stomata on leaves allow gas exchange and transpiration.
Q31.
The pigment that absorbs light energy:
Correct Answer: B) Chlorophyll
Chlorophyll in chloroplasts absorbs light for photosynthesis.
Chlorophyll in chloroplasts absorbs light for photosynthesis.
Q32.
Enzyme that digests proteins in stomach:
Correct Answer: B) Pepsin
Pepsin breaks down proteins in acidic stomach environment.
Pepsin breaks down proteins in acidic stomach environment.
Q33.
The powerhouse of the cell:
Correct Answer: A) Mitochondria
Mitochondria produce energy (ATP) through cellular respiration.
Mitochondria produce energy (ATP) through cellular respiration.
Q34.
Double circulation means:
Correct Answer: A) Blood passes through heart twice in one cycle
Systemic and pulmonary circulation - blood visits heart twice per complete circulation.
Systemic and pulmonary circulation - blood visits heart twice per complete circulation.
Q35.
Excretory unit of kidney:
Correct Answer: A) Nephron
Each kidney has about 1 million nephrons for filtration.
Each kidney has about 1 million nephrons for filtration.
Q36.
The gap between two neurons is called:
Correct Answer: B) Synapse
Synapse is junction where neurotransmitters transmit signals between neurons.
Synapse is junction where neurotransmitters transmit signals between neurons.
Q37.
Master gland of endocrine system:
Correct Answer: B) Pituitary
Pituitary gland controls other endocrine glands.
Pituitary gland controls other endocrine glands.
Q38.
Hormone secreted by pancreas:
Correct Answer: B) Insulin
Insulin regulates blood glucose levels.
Insulin regulates blood glucose levels.
Q39.
Iodine is necessary for synthesis of:
Correct Answer: A) Thyroxine
Thyroid gland needs iodine to produce thyroxine hormone.
Thyroid gland needs iodine to produce thyroxine hormone.
Q40.
Number of chromosomes in human body cell:
Correct Answer: B) 46
23 pairs = 46 chromosomes in somatic cells.
23 pairs = 46 chromosomes in somatic cells.
Q41.
Sex of child is determined by:
Correct Answer: A) Father
Father contributes X or Y chromosome; mother always contributes X.
Father contributes X or Y chromosome; mother always contributes X.
Q42.
The mirror formula is:
Correct Answer: A) 1/f = 1/v + 1/u
Relates focal length (f), object distance (u), and image distance (v) for mirrors.
Relates focal length (f), object distance (u), and image distance (v) for mirrors.
Q43.
The lens formula is:
Correct Answer: B) 1/f = 1/v - 1/u
For lenses: 1/f = 1/v - 1/u (with proper sign convention).
For lenses: 1/f = 1/v - 1/u (with proper sign convention).
Q44.
Power of lens formula:
Correct Answer: A) P = 1/f (in meters)
Power in diopters (D), focal length in meters.
Power in diopters (D), focal length in meters.
Q45.
SI unit of power of lens:
Correct Answer: B) Dioptre
Dioptre (D) is SI unit of lens power.
Dioptre (D) is SI unit of lens power.
Q46.
Refractive index formula:
Correct Answer: A) n = c/v
n = speed of light in vacuum / speed in medium.
n = speed of light in vacuum / speed in medium.
Q47.
Twinkling of stars is due to:
Correct Answer: A) Atmospheric refraction
Changing refractive index of atmosphere causes apparent position change.
Changing refractive index of atmosphere causes apparent position change.
Q48.
Ohm's law states:
Correct Answer: A) V = IR
Voltage = Current × Resistance (at constant temperature).
Voltage = Current × Resistance (at constant temperature).
Q49.
Electric power formula:
Correct Answer: A) P = VI
Power = Voltage × Current (also P = I²R = V²/R).
Power = Voltage × Current (also P = I²R = V²/R).
Q50.
Which is biodegradable?
Correct Answer: B) Paper
Paper decomposes naturally; plastic, glass, polythene are non-biodegradable.
Paper decomposes naturally; plastic, glass, polythene are non-biodegradable.
Disclaimer: We are not affiliated with NCERT. Although every care has been taken in creating this test, in case of any confusion, students should consider the NCERT textbooks and the opinion of their subject teacher as final.
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