← MES Jr. Grade
Past Questions
What is ‘milk of magnesia’ chemically?
A)
Magnesium carbonate
B)
Sodium carbonate
C)
Sodium hydroxide
D)
Magnesium hydroxide
Milk of Magnesia is a pharmaceutical suspension consisting of magnesium hydroxide [Mg(OH)₂] in water. It is commonly used as an antacid to neutralize excess stomach acid (HCl) and as a laxative.
Step-by-step analysis of options:
- Option (a) Magnesium carbonate (MgCO₃) is a different chemical compound used in some supplements but is not 'Milk of Magnesia'.
- Option (b) Sodium carbonate (Na₂CO₃), also known as soda ash, is a strong alkaline salt used in glass manufacturing and detergents.
- Option (c) Sodium hydroxide (NaOH), also known as caustic soda, is a strong base and is highly corrosive, making it unsuitable for ingestion as an antacid.
- Option (d) Magnesium hydroxide [Mg(OH)₂] is the correct chemical composition. It is a mild base that reacts with hydrochloric acid in the stomach to produce magnesium chloride and water, thereby relieving acidity.
Panchayati Raj was first introduced in India in which state?
A)
Maharashtra
B)
Gujarat
C)
Rajasthan
D)
Kerala
The Panchayati Raj system, which aims to establish democratic decentralization in India, was first formally inaugurated in the state of Rajasthan. It was launched on October 2, 1959, at Nagaur district by the then Prime Minister, Jawaharlal Nehru. This move was based on the recommendations of the Balwant Rai Mehta Committee (1957), which advocated for a three-tier system of Panchayati Raj (Gram Panchayat at the village level, Panchayat Samiti at the block level, and Zila Parishad at the district level).
Regarding the other options:
- Maharashtra and Gujarat adopted the system shortly after Rajasthan, but they were not the first.
- Kerala has a strong tradition of local self-governance, but the formal introduction of the modern Panchayati Raj system started in Rajasthan.
Petroleum is a mixture of:
A)
Hydrocarbons
B)
Elements
C)
Polymers
D)
Alcohols
Step-by-step reasoning:
1. Definition of Petroleum: Petroleum (from Latin 'petra' meaning rock and 'oleum' meaning oil) is a naturally occurring liquid found in geological formations.
2. Chemical Composition: Chemically, petroleum is a complex mixture of organic compounds consisting primarily of hydrogen and carbon atoms. Compounds made up exclusively of carbon and hydrogen are known as hydrocarbons.
3. Types of Hydrocarbons in Petroleum: It contains various types of hydrocarbons, including alkanes (paraffins), cycloalkanes (naphthenes), and aromatic hydrocarbons.
4. Evaluating Options:
- (a) Hydrocarbons: Correct. This is the primary chemical constituent of petroleum.
- (b) Elements: Incorrect. Petroleum is a mixture of compounds, not a pure element (though it is composed of elements like C and H).
- (c) Polymers: Incorrect. While some heavy fractions (like bitumen) have polymer-like properties, petroleum as a whole is not classified as a mixture of polymers.
- (d) Alcohols: Incorrect. Alcohols contain oxygen (hydroxyl group -OH). While trace amounts of oxygenated compounds may exist, petroleum is fundamentally a hydrocarbon mixture, not an alcohol mixture.
As per the Indian Stamp (Mizoram Amendment) Act, 2024, what is the stamp duty for mortgage of an immovable property by any person who is not a widow?
A)
1%
B)
2.5%
C)
3%
D)
5%
The Indian Stamp (Mizoram Amendment) Act, 2024, introduces revised rates for stamp duties within the state of Mizoram to streamline revenue and property transactions. Under the amended schedule for the mortgage of immovable property, a distinction is made based on the status of the mortgagor to provide social relief to certain groups. For a general person (any person who is not a widow), the prescribed stamp duty for the mortgage of immovable property is set at 3%. In contrast, the Act provides a concessional rate (typically lower, such as 1% or 2%) for widows to encourage financial accessibility for them. Therefore, option (c) is the correct rate for non-widows.
Which is the purest form of iron?
A)
Steel
B)
Cast iron
C)
Pig iron
D)
Wrought iron
To determine the purest form of iron, we must analyze the carbon content and impurities in each option:
1. **Pig Iron (Option c):** This is the immediate product of the blast furnace. It contains a very high carbon content (typically 3.5% to 4.5%), along with silicon, phosphorus, and sulfur. It is brittle and the least pure form of iron.
2. **Cast Iron (Option b):** Produced by remelting pig iron, it still contains a high carbon content (usually 2% to 4%). While more refined than pig iron, it is far from pure iron.
3. **Steel (Option a):** Steel is an alloy of iron and carbon. The carbon content is reduced to between 0.02% and 2.1%. While much purer than cast iron, it is specifically designed as an alloy.
4. **Wrought Iron (Option d):** This is produced by removing almost all the carbon from pig iron (often through the puddling process). It contains very little carbon (less than 0.08%) and consists primarily of nearly pure iron with small inclusions of slag.
Therefore, among the given options, wrought iron has the lowest carbon content and is considered the purest commercial form of iron.
In which year did the Jallianwala Bagh Massacre take place?
A)
1918
B)
1919
C)
1920
D)
1921
The Jallianwala Bagh Massacre occurred on April 13, 1919, in Amritsar, Punjab. The event took place when British troops, under the command of Brigadier-General Reginald Dyer, opened fire on a large crowd of unarmed civilians who had gathered for the festival of Baisakhi and to peacefully protest the Rowlatt Act (which allowed the government to imprison people without trial).
Analysis of options:
- a. 1918: Incorrect. This was the final year of World War I.
- b. 1919: Correct. The massacre took place on April 13 of this year.
- c. 1920: Incorrect. This year marked the beginning of the Non-Cooperation Movement led by Mahatma Gandhi, partly in response to the massacre.
- d. 1921: Incorrect. This year is associated with the height of the Non-Cooperation Movement and the Moplah Rebellion.
Which article of the Indian Constitution deals with the election of the President of India?
A)
Article 54
B)
Article 61
C)
Article 70
D)
Article 75
Step-by-step reasoning:
1. Article 54 of the Indian Constitution specifically defines the 'Electoral College' for the election of the President. It states that the President is elected by an electoral college consisting of the elected members of both Houses of Parliament and the elected members of the Legislative Assemblies of the States (and the National Capital Territory of Delhi and Puducherry).
2. Analysis of other options:
- Article 61: Deals with the procedure for the impeachment of the President.
- Article 70: Deals with the discharge of the President's functions in other contingencies not provided for in the Constitution.
- Article 75: Deals with other provisions as to Ministers (appointment, tenure, and responsibility), not the President's election.
Therefore, Article 54 is the correct provision regarding the election of the President.
The property of a species being unique to a defined geographic location is known as:
A)
Endemism
B)
Species evenness
C)
Ecotone
D)
Keystone
Step-by-step reasoning:
1. Analysis of the question: The question asks for the term that describes a species being unique to a specific, defined geographic location.
2. Evaluating Option (a) Endemism: In ecology, an endemic species is one that is native to a single defined geographic location, such as an island, state, nation, or other defined zone. This matches the definition provided in the question perfectly.
3. Evaluating Option (b) Species evenness: This refers to how close in numbers each species in an environment is. It is a measure of biodiversity, not geographic uniqueness.
4. Evaluating Option (c) Ecotone: An ecotone is a transition area between two biological communities, where two communities meet and integrate (e.g., the area between a forest and a grassland). It is a location, not a property of a species.
5. Evaluating Option (d) Keystone: A keystone species is one that has a disproportionately large effect on its natural environment relative to its abundance. While important, this refers to the species' functional role in an ecosystem, not its geographic restriction.
Conclusion: Option (a) is the only term that describes geographic uniqueness.
DNA fingerprinting was first invented by:
A)
James Watson
B)
Alec Jeffreys
C)
Har Gobind Khorana
D)
Paul Nurse
DNA fingerprinting (also known as DNA profiling) was developed in 1984 by Sir Alec Jeffreys at the University of Leicester. He discovered that certain sequences of DNA (called minisatellites) are highly variable between individuals, allowing for a unique genetic 'fingerprint' to be created for identification purposes.
Why other options are incorrect:
- James Watson: Co-discovered the double-helix structure of DNA in 1953 along with Francis Crick.
- Har Gobind Khorana: Known for his work on the genetic code and the first artificial synthesis of a functional gene.
- Paul Nurse: A geneticist and cell biologist known for his work on the cell cycle (specifically the cdc2 gene).
What number should come next in the following numbers series 2, 8, 18, 32, 50, ___?
A)
70
B)
71
C)
72
D)
73
To find the next number in the series 2, 8, 18, 32, 50, ___, we can analyze the pattern using two different methods:
Method 1: Difference Analysis
- The difference between 8 and 2 is 6.
- The difference between 18 and 8 is 10.
- The difference between 32 and 18 is 14.
- The difference between 50 and 32 is 18.
Observing the differences (6, 10, 14, 18), we see they increase by 4 each time. Therefore, the next difference should be 18 + 4 = 22.
Adding this to the last term: 50 + 22 = 72.
Method 2: Mathematical Formula
Each term in the series follows the formula 2 * (n²), where n is the position of the term:
- 1st term: 2 * (1²) = 2 * 1 = 2
- 2nd term: 2 * (2²) = 2 * 4 = 8
- 3rd term: 2 * (3²) = 2 * 9 = 18
- 4th term: 2 * (4²) = 2 * 16 = 32
- 5th term: 2 * (5²) = 2 * 25 = 50
- 6th term: 2 * (6²) = 2 * 36 = 72.
Both methods consistently lead to the answer 72. Options a, b, and d are incorrect as they do not follow the established mathematical progression of the series.
The boundary of a State can be altered through the provisions laid down in which Article of the Constitution?
A)
Article 3
B)
Article 13
C)
Article 23
D)
Article 33
Under the Constitution of India, Article 3 empowers the Parliament to alter the boundaries of existing states. Specifically, it allows Parliament by law to: (a) form a new state by separation of territory from any state or by uniting two or more states; (b) increase the area of any state; (c) diminish the area of any state; (d) alter the boundaries of any state; and (e) alter the name of any state.
Analysis of other options:
- Article 13: Deals with laws inconsistent with or in derogation of the Fundamental Rights.
- Article 23: Prohibits traffic in human beings and forced labour.
- Article 33: Empowers Parliament to modify the application of Fundamental Rights to members of the Armed Forces, paramilitary forces, police forces, etc.
Which gas is released when limestone is dipped in water?
A)
Hydrogen
B)
Oxygen
C)
Nitrogen
D)
Carbon dioxide
Limestone is primarily composed of calcium carbonate (CaCO3). Under normal conditions, pure limestone is virtually insoluble in pure water. However, in the context of chemistry exam questions of this type, the question typically refers to the reaction of limestone with an acidic solution (like rainwater containing dissolved CO2 or a dilute acid) or the decomposition of limestone. When calcium carbonate reacts with an acid (H+), it produces calcium salts, water, and carbon dioxide gas (CO2). The chemical equation is: CaCO3 + 2HCl → CaCl2 + H2O + CO2↑. Even in pure water, a very slow equilibrium exists where CO2 can be released if the limestone contains impurities or if the water is slightly acidic. Among the given options, Carbon dioxide is the only gas chemically associated with the decomposition or reaction of carbonates. Hydrogen, Oxygen, and Nitrogen are not produced by the reaction of limestone with water.
Which of the following statements is true of inferior goods?
A)
Demand decreases with increase in income
B)
Demand increases with increase in income
C)
Demand decreases with decrease in income
D)
Demand is independent of income
In economics, goods are categorized based on how demand for them changes relative to a consumer's income.
1. **Normal Goods**: These are goods for which demand increases as consumer income rises (positive income elasticity).
2. **Inferior Goods**: These are goods for which demand decreases as consumer income rises. This happens because as consumers earn more, they can afford more expensive, higher-quality substitutes. For example, if a person's income increases, they might stop buying generic brand staples (inferior goods) and start buying premium organic brands (normal goods).
Evaluating the options:
- **Option a**: Correct. This is the definition of an inferior good (negative income elasticity).
- **Option b**: Incorrect. This describes a 'Normal Good'.
- **Option c**: Incorrect. If demand decreases when income decreases, it means demand increases when income increases, which again describes a 'Normal Good'.
- **Option d**: Incorrect. This describes a good with zero income elasticity, which is not the characteristic of an inferior good.
Which Indian state shares the longest border with Myanmar?
A)
Mizoram
B)
Arunachal pradesh
C)
Manipur
D)
Tripura
India shares a total border of approximately 1,643 km with Myanmar. This border is shared by four Indian states: Arunachal Pradesh, Nagaland, Manipur, and Mizoram. Among these, Arunachal Pradesh shares the longest boundary with Myanmar, followed by Mizoram, Nagaland, and Manipur. Tripura does not share a border with Myanmar; it shares its borders with Bangladesh. Therefore, option (b) is the correct answer.
The product of force and velocity is known as:
A)
Work
B)
Power
C)
Energy
D)
Momentum
Step-by-step reasoning:
1. Definition of Power: In physics, power is defined as the rate at which work is done or energy is transferred. The formula for power is P = Work / time.
2. Relationship with Force: Work is defined as the product of force (F) and displacement (d) in the direction of the force (Work = F × d).
3. Derivation: Substituting the work formula into the power formula, we get P = (F × d) / t. Since displacement divided by time (d/t) is the definition of velocity (v), the formula becomes P = F × v.
4. Conclusion: Therefore, the product of force and velocity is known as Power.
Why other options are incorrect:
- a. Work: Work is the product of force and displacement (W = F × d), not velocity.
- c. Energy: Energy is the capacity to do work. While it has the same units as work (Joules), it is not the product of force and velocity.
- d. Momentum: Momentum is the product of mass and velocity (p = m × v), not force and velocity.
Which is NOT an example of a greenhouse gas?
A)
Methane
B)
Nitrous oxide
C)
Oxygen
D)
Carbon dioxide
Greenhouse gases (GHGs) are gases in Earth's atmosphere that trap heat by absorbing infrared radiation, contributing to the greenhouse effect.
1. **Carbon dioxide (CO2)**: A primary greenhouse gas emitted through natural processes and human activities like burning fossil fuels.
2. **Methane (CH4)**: A potent greenhouse gas emitted during the production of coal, natural gas, and oil, as well as from livestock and organic decay in landfills.
3. **Nitrous oxide (N2O)**: A powerful greenhouse gas emitted from agricultural and industrial activities, as well as during combustion of fossil fuels and solid waste.
4. **Oxygen (O2)**: Oxygen is a diatomic molecule with a symmetric structure. Because of this symmetry, it does not absorb infrared radiation and therefore does not contribute to the greenhouse effect. It is a vital gas for respiration but not a greenhouse gas.
Who among the following has been appointed as the Director of the Liquid Propulsion Systems Centre of ISRO?
A)
M. Mohan
B)
S. Somnath
C)
V. Narayanan
D)
K. Sivan
V. Narayanan is the Director of the Liquid Propulsion Systems Centre (LPSC), which is a major center of the Indian Space Research Organisation (ISRO) responsible for the design and development of liquid propulsion systems for launch vehicles.
Analysis of other options:
- M. Mohan: He is a senior scientist at ISRO, known for his work on the Mars Orbiter Mission (MOM), but is not the Director of LPSC.
- S. Somnath: He is the current Chairman of ISRO and Secretary of the Department of Space (DoS).
- K. Sivan: He is the former Chairman of ISRO (served from 2018 to 2022).
Arrange the following capital cities from northernmost to southernmost. I. Kolkata II. Jaipur III. New Delhi IV. Chandigarh
A)
IV, II, III, I
B)
III, II, IV, I
C)
IV, III, I, II
D)
IV, III, II, I
To arrange the cities from northernmost to southernmost, we look at their approximate latitudes:
1. Chandigarh (IV): Approximately 30.73° N
2. New Delhi (III): Approximately 28.61° N
3. Jaipur (II): Approximately 26.91° N
4. Kolkata (I): Approximately 22.57° N
Comparing these latitudes, Chandigarh is the furthest north, followed by New Delhi, then Jaipur, and finally Kolkata, which is the furthest south among the four.
Therefore, the correct sequence is IV (Chandigarh) → III (New Delhi) → II (Jaipur) → I (Kolkata).
A 100 kVA transformer has full-load Cu loss = 800 W. At 75% load, Cu loss = ?
A)
450 W
B)
600 W
C)
800 W
D)
700 W
Copper loss varies as the square of load current. At 75% load, the copper loss is (0.75)^2 times the full-load copper loss = 0.5625 × 800 = 450 W. So option (a) is correct.
Why others are wrong: (b) 600 W would correspond to a higher-than-actual fraction of full-load loss; (c) 800 W is the full-load copper loss, not the 75% load loss; (d) 700 W is also too high because copper loss decreases with the square of load, not linearly.
The time taken for response to reach 50% of the final value, for the very first time is called:
A)
Rise time
B)
Delay time
C)
Settling time
D)
Peak time
In control systems, specifically when analyzing the step response of a system, various time-domain specifications are used to describe the transient response:
1. **Delay Time (td):** This is defined as the time required for the response to reach 50% of its final value for the first time. It is a measure of how quickly the system starts responding to the input.
2. **Rise Time (tr):** This is the time required for the response to rise from 10% to 90% of its final value (for overdamped systems) or from 0% to 100% of its final value (for underdamped systems).
3. **Peak Time (tp):** This is the time required for the response to reach the first peak of the overshoot.
4. **Settling Time (ts):** This is the time required for the response to reach and stay within a specified tolerance band (usually 2% or 5%) of its final value.
Since the question specifically asks for the time taken to reach 50% of the final value for the first time, the correct term is Delay Time.
Distribution factor for a winding having 3 slots/pole phase and slot angle of 20° is:
A)
0.96
B)
1.0
C)
0.5
D)
0.707
The distribution factor (Kd), also known as the breadth factor, is used in electrical machines to account for the fact that coils in a slot are distributed over a certain angle rather than being concentrated in one slot.
1. **Given Data:**
- Number of slots per pole per phase (m) = 3
- Slot angle (β) = 20°
2. **Formula for Distribution Factor (Kd):**
Kd = (sin(mβ/2)) / (m * sin(β/2))
3. **Step-by-Step Calculation:**
- Calculate the numerator: mβ/2 = (3 * 20°) / 2 = 30°
sin(30°) = 0.5
- Calculate the denominator: m * sin(β/2) = 3 * sin(20°/2) = 3 * sin(10°)
sin(10°) ≈ 0.1736
Denominator = 3 * 0.1736 = 0.5208
4. **Final Result:**
Kd = 0.5 / 0.5208 ≈ 0.96006
Comparing this result to the options provided, 0.96 is the correct value.
- Option b (1.0) would be for a concentrated winding (m=1).
- Option c (0.5) and d (0.707) are mathematically incorrect for these specific parameters.
Plant capacity factor = Average load / Plant capacity. It is always:
A)
> Load factor
B)
< Load factor
C)
= Load factor
D)
Independent
To determine the relationship between Plant Capacity Factor and Load Factor, let's look at their mathematical definitions:
1. **Load Factor**: It is the ratio of the average load over a given period to the peak load during that same period.
Formula: Load Factor = Average Load / Peak Load
2. **Plant Capacity Factor**: It is the ratio of the average load over a given period to the rated capacity of the plant.
Formula: Plant Capacity Factor = Average Load / Plant Capacity
3. **The Relationship**: In any practical power system, the Plant Capacity (the maximum power the plant is designed to produce) must be greater than or equal to the Peak Load (the maximum power actually demanded by the consumers) to ensure system stability and reliability.
Mathematically: Plant Capacity ≥ Peak Load.
4. **Comparison**:
Since both formulas have the same numerator (Average Load), the one with the smaller denominator will have the larger value.
Because Plant Capacity ≥ Peak Load, it follows that:
(Average Load / Plant Capacity) ≤ (Average Load / Peak Load)
Therefore: Plant Capacity Factor ≤ Load Factor.
In real-world engineering scenarios, plants are designed with a reserve margin, meaning Plant Capacity is strictly greater than Peak Load, making the Plant Capacity Factor strictly less than the Load Factor.
In DC machine, material used for collection of current from the armature conductor is called:
A)
Brush
B)
Commutator
C)
Yoke
D)
None of the above
In a DC machine, the armature rotates, meaning the conductors are in motion. To transfer the electrical current from the rotating armature to the stationary external circuit, a sliding contact is required.
1. **Brushes (Option a):** These are stationary components (usually made of carbon or graphite) that press against the rotating commutator. Their primary function is to 'collect' the current from the commutator and deliver it to the external load or power supply. Therefore, they are the material used for the collection of current.
2. **Commutator (Option b):** The commutator is a mechanical rectifier. While it is the point of contact for the brushes, its primary role is to convert AC produced in the armature to DC (in a generator) or vice versa (in a motor). It is part of the rotating assembly, not the stationary collection mechanism.
3. **Yoke (Option c):** The yoke is the outer frame of the machine. Its purpose is to provide mechanical support and carry the magnetic flux; it has no role in current collection.
Conclusion: The brushes act as the interface that collects the current from the rotating armature conductors via the commutator.
Which losses are reduced by having laminated poles and pole shoes?
A)
Eddy current losses
B)
Hysteresis losses
C)
Iron losses
D)
Copper losses
In electrical machines, the poles and pole shoes are subjected to alternating magnetic flux (especially in AC machines or DC machines with ripple). This changing magnetic field induces electromotive forces (EMFs) within the conductive iron core of the poles. According to Faraday's Law, these EMFs cause circulating currents to flow within the bulk of the metal, known as 'Eddy Currents'. These currents result in I²R heating, which leads to energy loss. By laminating the poles (dividing the solid core into thin sheets insulated from each other), the path for these circulating currents is broken, significantly increasing the electrical resistance to the eddy currents and thereby reducing the eddy current losses.
Why other options are incorrect:
- b. Hysteresis losses: These are caused by the friction of magnetic domains flipping during magnetization. They depend on the material grade (e.g., silicon steel) rather than the physical structure (lamination).
- c. Iron losses: This is a general term that includes both Hysteresis and Eddy current losses. While laminations reduce iron losses, they specifically target the eddy current component, making 'a' the most precise answer.
- d. Copper losses: These occur due to the resistance of the winding wires (I²R losses) and are unrelated to the construction of the iron poles.
The analogous quantities of Storage element in force-voltage analogy (mechanical and electrical system) are:
A)
Velocity and Current
B)
Mass and Inductance
C)
Force and Voltage
D)
Spring stiffness and charge
In system modeling, the Force-Voltage (f-v) analogy is used to relate mechanical translational systems to electrical circuits. In this analogy, mechanical force (F) is analogous to electrical voltage (V), and velocity (v) is analogous to current (i).
Storage elements are components that can store energy. In a mechanical system, energy is stored in the form of kinetic energy (by mass) and potential energy (by a spring). In an electrical system, energy is stored in the form of magnetic energy (by an inductor) and electric energy (by a capacitor).
1. Kinetic Energy Storage: Mass (M) stores energy as 1/2 Mv². In the f-v analogy, Mass (M) is analogous to Inductance (L), which stores energy as 1/2 Li².
2. Potential Energy Storage: A Spring (with stiffness k) stores energy as 1/2 kx². In the f-v analogy, the reciprocal of stiffness (1/k, or compliance) is analogous to Capacitance (C).
Evaluating the options:
- Option (a): Velocity and Current are 'flow' variables, not storage elements.
- Option (b): Mass and Inductance are both storage elements (storing kinetic/magnetic energy) and are analogous in the f-v system. This is correct.
- Option (c): Force and Voltage are 'effort' variables, not storage elements.
- Option (d): Spring stiffness is a property of a storage element, but charge is a state variable (analogous to displacement), not a storage element itself.