Ecology & Environmental Science

Ecology & Environmental Science

A cut trunk shows 26 concentric rings of spring wood and autumn wood in alternate rows. The age of trunk would be:

Each annual growth ring consists of one light spring earlywood and one dark autumn latewood. One year produces pair of rows. Counting 26 alternating rows thus represents 13 annual rings, indicating 13 years of secondary growth.

Ref: Taiz and Zeiger, Plant Physiology, 6th Edition, Chapter 27 Secondary Growth and Growth Rings, explains annual ring formed by spring earlywood and autumn latewood pair, so 26 rows equals 13 years age, published by Sinauer Associates.

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Ecology & Environmental Science

Wood pulp is used to make which of the following: A) Paper bags B) Calendars C) Cardboard boxes D) Tissue and toilet pap

Wood pulp cellulose fibers are feedstock for paper bags, calendars, cardboard boxes, tissues, building insulation batts, disposable hygiene products and even nonwoven blanket bases. All listed categories A through G utilize pulp directly or as processed fiber.

Ref: Rowell, Handbook of Wood Chemistry and Wood Composites, 2nd Edition, Chapter 3 Pulp and Paper Products, enumerates uses of wood pulp for paper bags calendars cardboard tissues insulation blankets diapers sanitary products, published by CRC Press.

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Ecology & Environmental Science

A bus is moving with a speed of 10 m/s on a straight road. A scooterist wishes to overtake the bus in 100 s. If the bus

Scooter must cover initial 1000 m separation plus distance bus travels in 100 seconds. Bus covers 10 into 100 equals 1000 m. Total 2000 m in 100 s requires 20 m/s. Relative velocity concept yields same result.

Ref: Young and Freedman, University Physics, 14th Edition, Chapter 2 Linear Kinematics, derives relative motion overtaking problem using distance equals velocity times time for bus and scooter pursuit, published by Pearson.

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Ecology & Environmental Science

If an iron ball and a wooden ball of same radii are released from a height ‘h’ in vacuum then time taken by both of them

In vacuum no air resistance, acceleration due to gravity is independent of mass or composition per equivalence principle. Both balls start from rest and follow h equals half g t squared. Therefore they reach ground simultaneously despite different densities.

Ref: Resnick, Halliday and Walker, Fundamentals of Physics, 10th Edition, Chapter 2 Motion and Universal Gravitation, describes equivalence principle where gravitational acceleration in vacuum independent of mass yielding equal fall times, published by Wiley.

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Ecology & Environmental Science

Water at 24 degrees Celsius feels much colder than air at the same temperature and our body loses heat many times more q

Water conducts heat about 23 times faster than air and its higher density provides greater volumetric heat capacity, accelerating heat removal from skin. Feeling wetness does not explain chilling. Thus higher conductivity and density both explain rapid cooling.

Ref: Hall, Guyton and Hall Textbook of Medical Physiology, 14th Edition, Chapter 73 Body Temperature Regulation, explains water's higher thermal conductivity and density causing faster heat loss than air at same temperature, published by Elsevier.

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Ecology & Environmental Science

Legal limit of blood alcohol concentration as per traffic rules in India is:

Under Section 185 of Motor Vehicles Act, India prescribes 30 mg alcohol per 100 ml blood as permissible limit for private drivers. Exceeding this constitutes drunken driving offense punishable by fine and imprisonment. Higher values belong to other jurisdictions.

Ref: Reddy, The Essentials of Forensic Medicine and Toxicology, 34th Edition, Chapter 9 Alcohol Intoxication, states legal blood alcohol limit in India is 30 mg per 100 ml blood under Motor Vehicles Act Section 185, published by Jaypee Brothers.

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Ecology & Environmental Science

A piece of ice floats in a vessel with water above which a layer of a lighter oil is poured. How will the level of the i

Floating ice satisfies Archimedes principle. Melted ice converts to smaller water volume than ice volume, lowering total oil top level. However meltwater adds to water phase, increasing its volume and raising oil-water interface. Hence interface rises while overall liquid level falls.

Ref: Cengel and Cimbala, Fluid Mechanics: Fundamentals and Applications, 3rd Edition, Chapter 3 Hydrostatic Forces and Buoyancy, analyzes ice floating at oil-water interface, meltwater addition raising interface while total volume contracts, published by McGraw-Hill.

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Ecology & Environmental Science

Hypo is used in photography because it is:

Sodium thiosulfate, hypo, dissolves unexposed silver bromide by forming soluble complex [Ag(S2O3)2]3-, fixing image and preventing further darkening. Its complexing ability removes residual photosensitive halide rather than acting as reductant or oxidant.

Ref: Stroebel et al., Focal Encyclopedia of Photography, 4th Edition, Chapter Fixation, describes sodium thiosulfate hypo as complexing agent forming silver thiosulfate to dissolve unexposed silver bromide, published by Focal Press.

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Ecology & Environmental Science

Two ice cubes are pressed over each other until they unite to form one block. The force mainly responsible for holding t

Pressing ice causes local pressure melting and refreezing, known as regelation, joining blocks. Ice lattice is held by extensive hydrogen bonds between water molecules. Restoring hydrogen bonding across interface fuses cubes, not van der Waals or covalent forces.

Ref: Atkins and de Paula, Physical Chemistry, 11th Edition, Chapter 17 Intermolecular Forces and Chapter 5 phase equilibria, discusses regelation and hydrogen bonding holding ice cubes together after pressure melting, published by Oxford University Press.

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Ecology & Environmental Science

In the table below are shown temperature conversions from Celsius (C) to Fahrenheit (F). Which of the following are corr

Fahrenheit equals Celsius times nine fifths plus 32. Zero Celsius equals 32 Fahrenheit, minus ten equals 14, minus forty equals minus forty where scales intersect. Hundred Celsius equals 212 Fahrenheit, not 180, so combination A, B, D is correctly matched.

Ref: Serway and Jewett, Physics for Scientists and Engineers, 10th Edition, Chapter 19 Temperature Scales, explains Celsius to Fahrenheit conversion formula F equals 9/5 C plus 32 and equality at minus 40 degrees, published by Cengage.

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Ecology & Environmental Science

A well stoppered thermos flask contains some ice cubes. This is an example of:

A well stoppered thermos flask prevents exchange of both matter and heat with surroundings due to vacuum and insulated cap. Such system with no mass or energy transfer defines isolated system, distinct from closed or open systems.

Ref: Zemansky and Dittman, Heat and Thermodynamics, 7th Edition, Chapter 2 Thermodynamic Systems, defines isolated system as no exchange of matter or energy exemplified by stoppered thermos flask, published by McGraw-Hill.

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Ecology & Environmental Science

Which of the following fractions of petroleum has the lowest boiling point?

Petroleum distillation separates fractions by boiling point. Gasoline with C4-C12 hydrocarbons boils at 40-200°C, lower than kerosene, diesel and heavy oil which contain longer chains. Hence gasoline vaporizes first and has lowest boiling point among options.

Ref: Speight, The Chemistry and Technology of Petroleum, 5th Edition, Chapter 4 Fractional Distillation, lists gasoline C4 to C12 with lowest boiling point among kerosene diesel heavy oil fractions, published by CRC Press Taylor Francis.

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