Top 30 Science MCQs for TNPSC,TN TRB,TNUSRB Exams

பல்வேறு போட்டித் தேர்வுகளில் அறிவியல் முக்கியப் பங்காற்றுகிறது, விண்ணப்பதாரர்களுக்கு அவர்களின் தயாரிப்பில் உதவ, நாங்கள் 30 கேள்விகளை (MCQs) தொகுத்துள்ளோம். உங்கள் அறிவியல் அறிவை மேம்படுத்துவதற்கும், வரவிருக்கும் தேர்வுகளுக்கு உங்களை சிறப்பாக தயார்படுத்துவதற்கும் ஒவ்வொரு கேள்விக்கும் சரியான பதில் உள்ளது.

Q1. Which of the following is the molecular formula of phenol?

(a) C6H5OH

(b) COOH

(d) C6H12O6

Q2. Which of the following statements is true about phenol?

(a) Phenol is a colorless solution that turns red in the presence of dust.

(b) Phenol is a blue solution that turns red in the presence of dust.

(d) Phenol is a red solution that turns blue in the presence of dust.

Q3. Which of the following is the correct molecular formula of Plaster of Paris?

(a) CaSO4

(b) CaSO4 .1/2H2O

(d) CaSO4 .3H2O

Q4. Which of the following is NOT a use of Plaster of Paris?

(a) Making blackboard chalks.

(b) Setting fractured bones in surgery.

(d) Use in the food industry.

Q5. What is the molecular formula of Epsom salt?

(a) MgSO4

(b) MgSO4 .1H2O

(d) MgSO4 .7H2O

Q6. Which of the following is NOT a use of Epsom salt?

(a) Eases stress and relaxes the body.

(b) Helps muscles and nerves function properly.

(d) Enhances the taste of food.

Q7. What is the chemical name of gypsum?

(a) Calcium carbonate

(b) Calcium sulfate dihydrate

(d) Sodium sulfate

Q8. Which of the following is NOT a use of gypsum?

(a) Used as fertilizers.

(b) Used in the process of making cement.

(d) Used in the manufacturing of glass.

Q9. What materials were used by Joseph Aspdin to invent Portland cement?

(a) Chalk and clay

(b) Limestone and sand

(d) Gravel and shale

Q10. Why are earthworms known as “Farmers’ friends”?

(a) They help in the production of compost castings.

(b) They consume organic waste as food.

(d) All of the above.

Q11. Which type of fertilizers are prepared by making natural elements undergo chemical changes in factories?

(a) Organic fertilizers

(b) Synthetic fertilizers

(d) Biofertilizers

Q12. Which type of fertilizers are made up of plant or animal-based materials or synthesized by microorganisms?

(a) Inorganic fertilizers

(b) Synthetic fertilizers

(d) Chemical fertilizers

Q13. Which of the following nutrients are known as Principal Nutrients for plant growth?

(a) Nitrogen (N), Phosphorous (P), and Potassium (K)

(b) Calcium (C(a), Magnesium (Mg), and Iron (Fe)

(d) Sulphur (S), Boron ((b), and Molybdenum (Mo)

Q14. What is the main difference between chemical changes and physical changes?

(a) Chemical changes involve a change in the substance itself, while physical changes only alter its shape, size, or volume.

(b) Chemical changes result in a change of state, while physical changes do not.

(d) Chemical changes involve a change in temperature, while physical changes do not.

Q15. Which of the following processes add water vapour to the atmosphere?

Transpiration
Precipitation

iii. Condensation

Evaporation

(a) ii and iii

(b) ii and iv

(d) i and ii

Q16. Which of the following locations in Tamil Nadu are examples of swamps?

(a) Pichavaram Mangroves in Chidambaram

(b) Muthupet mangrove wetland

(d) All of the above

Q17. Which of the following statements about estuaries is correct?

(a) Estuaries are wetlands where freshwater and saltwater meet.

(b) Estuaries are exclusively home to marine species.

(d) Estuaries do not support any plant or animal species.

Q18. The SI unit of heat is

(a) Erg

(b) Joule

(d) Kilocalorie

Q19. What is the S.I unit of electric potential difference?

(a) Volt

(b) Ampere

(d) Coulomb

Q20. Which of the following is not a unit of Energy?

(a) Calorie

(b) Phon

(d) B. T. U

Q21. Which one of the following cannot be the unit of Pressure?

(a) Pascal

(b) Kg/(ms2)

(d) N/m2

Q22. [ M-1L3T-2] are the dimensions of_____?

(a) Gravitational intensity

(b) Gravitational potential

(d) Gravitational constant

Q23. Which of the following statements accurately describes the relationship between astronomical units (AU) and light years (ly)?

(a) One astronomical unit is equal to 1 light year.

(b) One light year is equal to 1 astronomical unit.

(d) One light year is smaller than one astronomical unit.

Q24. Which of the following is NOT a scalar quantity?

(a) Angular Velocity

(b) Density

(d) Temperature

Q25. What are the units of the refractive index?

(a) Meter/Sec

(b) Meter/Sec2

(d) Newton/meter

Q26. Match the two correctly.

List A (S. I units) List B (Value)
i. Newton a. 1 kg⋅m^2⋅s^(-2)
ii. Pascal b. 1 kg⋅m^2⋅s^(-3)
iii. Joule c. 1 kg⋅m^(-1)⋅s^(-2)
iv. Watt d. 1 kg⋅m/s^2

(a) i-d , ii-c , iii-a , iv-b

(b) i-b , ii-a , iii-c , iv-d

(d) i-a , ii-b , iii-d , iv-c

Q27. SI unit of mass is Kg, what is the SI unit of weight?

(a )kg/s2

(b) Newton

(d) kg m/s

Q28. In a uniform circular motion:

(a) Distance is constant

(b) Speed is constant

(d) Velocity is constant

Q29. The formula for ﬁnding acceleration is:

(a) (vxt)

(b) (v – u)/t

(d) (1/t)

Q30. Distance covered by an object per unit time is called:

(a) Acceleration

(b) Motion

(d) Pressure

Solution:

S1. Ans. (a) C6H5OH.

Sol.

Phenol’s molecular formula is C6H5OH, as mentioned in the given information.
Phenol is a carbolic acid and an organic compound.
It is a necessary ingredient for preparing a variety of phenol products.
The molecular formula of phenol is C6H5OH.
This means that phenol consists of a benzene ring (C6H6) with a hydroxyl group (-OH) attached to it.
The hydroxyl group is what makes phenol a weak acid.

S2. Ans. (a) Phenol is a colorless solution that turns red in the presence of dust.

Sol.

Phenol is described as a colorless solution that changes into red when exposed to dust.

S3. Ans. (b) CaSO4 . 1/2H2O.

Sol.

The molecular formula of Plaster of Paris is CaSO4 . 1/2H2O. This indicates that Plaster of Paris consists of one calcium sulfate molecule (CaSO4) combined with half a water molecule (1/2H2O).

S4. Ans. (d) Use in the food industry.

Sol.

Plaster of Paris is used in making blackboard chalks, setting fractured bones in surgery, and making casts for statues and toys. However, it is not used in the food industry.
Plaster of Paris is primarily used in various applications such as construction, arts and crafts, and medical purposes, but it is not safe for consumption and is not used in the food industry.

S5. Ans. (d) MgSO4 . 7H2O.

Sol.

The molecular formula of Epsom salt is MgSO4 . 7H2O. This indicates that Epsom salt consists of one magnesium sulfate molecule (MgSO4) combined with seven water molecules (7H2O).

S6. Ans. (d) Enhances the taste of food

Sol.

Epsom salt is used for easing stress and relaxing the body, helping muscles and nerves function properly, and as a medicine for skin problems. However, it is not used to enhance the taste of food.
Epsom salt is primarily utilized for its therapeutic and medicinal properties, and it is not intended for culinary purposes.

S7. Ans. (b) Calcium sulfate dihydrate.

Sol.

The chemical name of gypsum is calcium sulfate dihydrate.

S8. Ans. (d) Used in the manufacturing of glass.

Sol.

Gypsum is used as fertilizers, in the process of making cement, and in the production of Plaster of Paris. However, it is not used in the manufacturing of glass.
Gypsum has various industrial applications, but glass manufacturing typically does not involve the use of gypsum.

S9. Ans. (a) Chalk and clay.

Sol.

Joseph Aspdin invented Portland cement by burning finely ground chalk and clay in a kiln.
These two materials, chalk and clay, were the key components used in the invention of Portland cement.
The process involved heating the mixture of chalk and clay in a kiln to produce a finely ground powder that would later become Portland cement.

S10. Ans. (d) All of the above

Sol .

Earthworms are known as “Farmers’ friends” because they provide a multitude of services that benefit farmers and improve soil health.
Earthworms help in the production of compost castings by consuming organic wastes as food and converting them into nutrient-rich castings.
These castings, also known as vermicompost, are valuable for enhancing soil fertility and providing essential nutrients to plants.
Additionally, earthworms contribute to improving soil health through their burrowing activity, which enhances soil aeration, drainage, and nutrient cycling.
Therefore, earthworms are considered beneficial allies to farmers due to the various services they offer in promoting sustainable agriculture and plant growth.

S11. Ans. (c) Inorganic fertilizers

Sol.

The fertilizers prepared by making natural elements undergo chemical changes in factories are called inorganic fertilizers.
Examples of inorganic fertilizers mentioned include Urea, Ammonium sulphate, and Super phosphate.
Inorganic fertilizers are manufactured through industrial processes that involve the chemical transformation of natural elements to create nutrient-rich compounds that can be readily absorbed by plants.
These fertilizers are widely used in agriculture to supplement soil nutrients and enhance plant growth.

S12. Ans.(c) Organic fertilizers

Sol.

Fertilizers containing only plant or animal-based materials or those synthesized by microorganisms are called organic fertilizers.
Examples of organic fertilizers mentioned include Vermicompost and compost. Organic fertilizers are derived from natural sources and can be prepared easily.
They provide nutrients to plants in a slow-release manner, improving soil fertility and promoting sustainable agriculture.
Organic fertilizers are often considered economical as they can be produced locally using readily available materials and do not involve complex industrial processes.

S13. Ans. (a) Nitrogen (N), Phosphorous (P), and Potassium (K).

Sol.

Nitrogen (N), Phosphorous (P), and Potassium (K) are the three important nutrients known as Principal Nutrients for plant growth.
These three elements play essential roles in various physiological processes of plants and are required in relatively large quantities compared to other nutrients.
Nitrogen is important for vegetative growth and protein synthesis, phosphorus is crucial for root development and energy transfer, and potassium contributes to overall plant health, water regulation, and disease resistance.

S14. Ans. (a)

Sol.

Chemical changes involve a change in the substance itself, while physical changes only alter its shape, size, or volume
Chemical changes result in the change of the substance, meaning its chemical composition is altered.
In contrast, physical changes only affect the physical characteristics of the substance, such as its shape, size, or volume, without changing its chemical identity.
While physical changes can involve changes in the state of matter (e. g. , from liquid to gas or solid, the substance remains the same chemically.

S15. Ans.(a). ii and iii: Precipitation and condensation.

Sol.

Precipitation refers to the process where water droplets or ice crystals fall from the atmosphere to the Earth’s surface in the form of rain, snow, sleet, or hail. This adds water vapor to the atmosphere.
Condensation is the process of water vapor changing into liquid water.
When warm air containing water vapor cools down, the vapor condenses and forms clouds or dew. This process also adds water vapor to the atmosphere.

S16. Ans.(d) All of the above.

Sol.

Pichavaram Mangroves in Chidambaram, Muthupet mangrove wetland, and Pallikaranai wetland in Chennai are all examples of swamps in Tamil Nadu.
These locations are characterized by wetlands that are forested and occur along large rivers or the shores of large lakes.
Swamps can have different types of water, including freshwater, brackish water, or seawater.
These swamps play a vital role in providing fresh water and oxygen to support diverse forms of life.

S17. Ans.(a) Estuaries are wetlands where freshwater and saltwater meet.

Sol. Coovam is an estuary. Estuaries are wetlands where water bodies meet the sea.

It is a combination of fresh water from land meeting the salty seawater.

Estuaries are home to unique plants and animal species.

S18. Ans. (b) Joule.

Sol.

Heat is the energy that is transferred from one body to another as the result of a difference in temperature and the S.I unit of heat is Joule.

One joule equals the work done.
A calorie is the amount of heat needed to raise the temperature of one gram of water by one degree Celsius.
A kilocalorie is equal to one thousand calories.

S19. Ans. (a) Volt.

Sol.

Volt is indeed the SI unit of electric potential difference.
Coulomb is indeed the SI unit of electric charge.
Joule is indeed a derived unit of energy.
Ampere is indeed the SI unit of electric current.

S20. Ans. (b) Phon.

Sol. Phon is not a unit of Energy.

Phon is a unit of the perceived loudness of sound for pure tones.

Calorie: It represents the amount of energy required to raise the temperature of one gram of water by one degree Celsius. It is often used to measure the energy content of food.
Kilowatt-hour (kWh): It represents the amount of energy consumed when a device with a power rating of one kilowatt operates for one hour.
B.T.U. (British Thermal Unit): It represents the amount of energy required to raise the temperature of one pound of water by one degree Fahrenheit.

S21. Ans. (b) Kgm/s2.

Sol.

The pressure is the perpendicular force acting per unit area.

SI unit of pressure is Pascal, which is equivalent to 1 N force acting per sq. meter.

It is given by, P = F/A

kgm/s² is the SI unit of force and not of pressure.

S22. Ans. (d) the gravitational constant,

Sol.

The dimensions M-1L3T-2 correspond to the gravitational constant. The gravitational constant, denoted by G, appears in the equation for Newton’s law of universal gravitation and determines the strength of the gravitational force between two objects. Its dimensions are M-1L3T-2, where M represents mass, L represents length, and T represents time.

S23. Ans. (c) One astronomical unit is smaller than one light year.

Sol.

An astronomical unit (AU) is defined as the average distance between the Earth and the Sun, approximately 149.6 million kilometers or 1.496 × 10^11 meters. It is primarily used to measure distances within our solar system.
On the other hand, a light year (ly) is defined as the distance that light travels in a vacuum in one year. It is an astronomical measurement primarily used to express vast distances between celestial objects outside our solar system. One light year is equal to approximately 9.46 × 10^15 meters.
Comparing the values, we can see that one light year is significantly larger than one astronomical unit.

S24. Ans. (a) Angular velocity

Sol.

Angular velocity is a vector quantity.
It represents the rate at which an object rotates or revolves around a specific axis.
Angular velocity has both magnitude and direction, making it a vector quantity.
The magnitude of angular velocity is given by the change in angular displacement per unit time. It is usually measured in radians per second (rad/s) or degrees per second (°/s).

S25. Ans. (c) No units.

Sol.

Refractive index of a material is a dimensionless number that describes how fast light travels through the material. It is defined as the ratio of the speed of light in vacuum to the phase velocity of light in the medium.

S26. Ans. (a) i-d, ii-c, iii-a, iv-b

Sol.

Newton is the SI unit of force, which has the value of 1 kg⋅m/s^2.
Pascal is the SI unit of pressure, which is defined as 1 N/m^2 or 1 kg⋅m^(-1)⋅s^(-2).
Joule is the SI unit of energy and work, which is defined as 1 N⋅m or 1 kg⋅m^2⋅s^(-2)
Watt is the SI unit of power, which is defined as 1 J/s or 1 kg⋅m^2⋅s^(-3).

S27. Ans. (b) Newton

Sol.

SI unit of mass is kg, and the SI unit of weight is Newton. Mass and weight are related but different concepts. Mass is a measure of the amount of matter in an object and is measured in kilograms (kg). Weight, on the other hand, is the force experienced by an object due to gravity and is measured in Newtons (N).

S28. Ans. (c) Displacement is constant

Sol.

In a uniform circular motion, the answer is Displacement is constant. In uniform circular motion, an object moves in a circular path with a constant speed but continuously changes its direction. The displacement refers to the change in position of the object from the initial to the final position, and in uniform circular motion, the displacement is constant as the object returns to its starting point.

S29. Ans. (b) (v – u)/t

Sol.

The formula for finding acceleration is (v – u)/t, where v is the final velocity, u is the initial velocity, and t is the time taken. Acceleration is a measure of how quickly the velocity of an object changes over time. The formula for acceleration is the change in velocity divided by the time taken.

S30. Ans. (c ) Speed

Sol.

Distance covered by an object per unit time is called Speed. Speed is defined as the distance traveled by an object divided by the time taken. It is a scalar quantity that only considers the magnitude of the motion, not the direction.

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