Nano Technology And Applications

Step 1: Understand the sequence of operations in a power supply.
1. Transformer (C): First step in converting AC voltage, stepping it up or down.
2. Rectifier (B): Converts AC to DC by using diodes to rectify the AC signal.
3. Filter (D): Smoothens the rectified DC voltage by reducing fluctuations.
4. Voltage regulator (A): Maintains a constant DC voltage, even if the input voltage varies.
Step 2: Conclusion.
The correct order of operation is:
Final Answer:

Step 1: Recall the laws of reflection and refraction.
- Reflection: angle of incidence = angle of reflection.
- Refraction: Snell’s law, .
Step 2: Universality.
Both laws hold true regardless of surface shape or media, but they are defined precisely at the point of incidence, where the light ray meets the boundary.
Final Answer:

Step 1: Check each option.
- Electron-volt (eV): energy unit (1 eV = J).
- Joule (J): SI unit of energy ( ).
- Newton-metre (N·m): equivalent to Joule, hence energy unit.
- Pascal (Pa): unit of pressure ( ).
Step 2: Conclusion.
Therefore, Pascal is not a unit of energy.
Final Answer:

Step 1: Recall Huckel’s rule.
For aromaticity, a compound must have electrons ( ).
Step 2: Structural requirements.
- Must be cyclic.
- Must be fully conjugated (p-orbitals overlap).
- Must be planar (allowing delocalization).
Step 3: Evaluate statements.
All four conditions (A, B, C, D) are required for aromaticity.
Final Answer:

Step 1: Understanding the process.
Cracking is a process in petroleum refining where high molecular weight hydrocarbons (long chains) are broken into smaller, more useful hydrocarbons.
Step 2: Types of cracking.
- Thermal cracking (heat).
- Catalytic cracking (using zeolite catalysts).
Step 3: Eliminate other options.
- Decomposition: general breakdown, not specific to hydrocarbons.
- Catenation: ability of atoms (like carbon) to form chains.
- Combustion: reaction with oxygen giving and .
Thus, the correct answer is Cracking.
Final Answer:

Step 1: Properties of malignant cells.
Malignant cancer cells are characterized by:
- Unregulated/continuous cell division.
- Ability to resist apoptosis (programmed cell death).
- Cellular immortality (no replicative senescence).
- Induction of angiogenesis to provide blood supply for rapid growth.
Step 2: Identifying the exception.
Since malignant cells promote (not inhibit) angiogenesis, the incorrect option is “inhibition of angiogenesis.”
Final Answer:

Step 1: Recall resistor colour code.
Digits: black–0, brown–1, red–2, orange–3, yellow–4, green–5, blue–6, violet–7, grey–8, white–9.
Step 2: Apply to given resistance.
Value: .
- First digit (2) → red.
- Second digit (4) → yellow.
- Multiplier ( ) → blue (6). So, colour code = red, yellow, blue.
Final Answer:

Step 1: Understanding racemic mixtures.
A racemic mixture contains equal amounts of two enantiomers (optical isomers). Their optical rotations cancel each other.
Step 2: Correct statements.
- Designated as (±).
- Plane polarized light remains unchanged because optical activities cancel.
- (+)-2-butanol alone is not racemic, but if mixed with its (–) enantiomer in equal proportion, it forms a racemic mixture.
Step 3: Identifying the incorrect option.
Since racemic mixtures are optically inactive, they do not cause finite rotation of plane polarized light.
Final Answer:

- DNA footprinting (A): This method identifies DNA binding sites of proteins, so it matches with (III) DNA binding proteins.
- Yeast two hybrid system (B): This system detects protein-protein interactions, hence it matches with (I) Protein-Protein interaction.
- DNA Fingerprinting (C): This technique uses VNTR (Variable Number Tandem Repeats) to identify individuals, so it matches with (II) VNTR.
- SAGE (D): SAGE is used for transcriptome analysis, so it matches with (IV) Transcriptome analysis.
Step 2: Conclusion.
Thus, the correct matching is:
Final Answer:

Step 1: Define three-terminal devices.
- A three-terminal device has three terminals: one for input, one for output, and one for control.
- Zener diode and photodiode are two-terminal devices.
- Bipolar Junction Transistor (BJT) and Field Effect Transistor (FET) are both three-terminal devices. The three terminals are the collector, base, and emitter for BJTs, and the source, gate, and drain for FETs.
Step 2: Conclusion.
Thus, the three-terminal devices are BJT (C) and FET (D).
Final Answer:

Step 1: Fischer projection formula rules.
- Fischer projections represent molecules in a 2D plane with vertical and horizontal bonds to show the configuration of stereoisomers.
- (A): Fischer projections must be in the plane of the paper to represent the correct 3D configuration.
- (B): The molecule can be flipped over in the Fischer projection, but it would reverse the configuration of the chiral centers, which is not allowed in certain cases.
- (C): Fischer projections can be rotated by 90° in the plane, and the configuration remains the same for simple molecules.
- (D): A 180° rotation of a Fischer projection would change the configuration, so it is not allowed.
Step 2: Conclusion. Thus, the correct option is:
Final Answer:

Step 1: Recall the regions of the hydrogen spectral series.
- Lyman series: UV (shortest wavelength, highest energy).
- Balmer series: Visible light.
- Paschen series: Infrared.
- Brackett series: Infrared (longer wavelength than Paschen).
Step 2: Increasing wavelength order.
The order of increasing wavelength corresponds to increasing energy levels in the electron transitions. Longer wavelengths correspond to transitions that occur from lower energy levels.
Step 3: Conclusion.
Thus, the order of increasing wavelength is:
Final Answer:

Step 1: Understanding superoxide dismutase.
Superoxide dismutase (SOD) is an important antioxidant enzyme that protects cells from oxidative stress.
Step 2: Reaction catalyzed.
It catalyzes the dismutation of superoxide radicals ( ) into hydrogen peroxide ( ) and oxygen ( ):
Final Answer:

Step 1: Reactivity principle.
Nucleophilic addition to aldehydes depends on: - Electronic effects (electron-donating/withdrawing groups).
- Steric hindrance (bulkiness near carbonyl carbon).
Step 2: Compare aldehydes.
- Formaldehyde ( ): No alkyl or aryl group → least steric hindrance, highly electrophilic.
- Acetaldehyde ( ): One group → slightly less reactive.
- Crotonaldehyde ( ): Conjugation with double bond → less reactive.
- Benzaldehyde ( ): Conjugation with aromatic ring → strongly deactivated carbonyl carbon.
Step 3: Conclusion.
Formaldehyde is the most reactive aldehyde toward nucleophilic addition.
Final Answer:

Step 1: Recall equivalent definitions.
Reduction = gain of electrons, loss of oxygen, gain of hydrogen, or oxidation number.
Step 2: Evaluate options.
(1) Gain of oxygen oxidation (not reduction).
(2) Increase in oxidation state oxidation.
(3) Gain of hydrogen reduction (correct).
(4) Loss of electrons oxidation (reduction is gain of electrons).
Final Answer:

Step 1: Newton's Law of Cooling.
Newton’s law of cooling states that the rate of change of temperature of an object is proportional to the difference between the object’s temperature and the ambient temperature.
Step 2: Stefan's Law.
Stefan-Boltzmann law describes how the energy radiated by a black body is proportional to the fourth power of its temperature ( ). The cooling of an object due to radiation can be modeled by this law in the context of temperature difference between the body and its surroundings.
Step 3: Conclusion.
Thus, Newton’s law of cooling is essentially a special case of Stefan's law where the temperature difference is small and the radiation is in the linear regime.
Final Answer:

Step 1: Recall the tests.
- Tollens’ test: Benzaldehyde (an aldehyde) gives a silver mirror; acetophenone (a ketone) does not.
- DNP test: Both aldehydes and ketones give positive 2,4-DNP test (orange/yellow ppt), so not distinguishing.
- Iodoform test: Acetophenone (methyl ketone) gives yellow ppt of ; benzaldehyde does not.
- Carbylamine test: Detects primary amines, not aldehydes/ketones.
Step 2: Conclusion.
Thus, acetophenone and benzaldehyde can be distinguished by Tollens reagent and Iodoform test.
Final Answer:

Step 1: Mechanism of S reaction.
The S reaction (bimolecular nucleophilic substitution) requires a backside attack on the electrophilic carbon. It typically occurs with primary or secondary alkyl halides, as well as with benzyl and allyl halides.
Step 2: Analyze each halide.
- Chlorobenzene (A): The carbon attached to the halogen is sp hybridized, making it very resistant to nucleophilic attack. It does not undergo an S reaction.
- Benzyl chloride (B): The benzyl group stabilizes the transition state, making this halide very reactive in an S reaction.
- Tertiary-butyl chloride (C): Due to the steric hindrance around the tertiary carbon, this halide does not undergo S reactions but follows an S 1 mechanism.
- n-butyl chloride (D): This is a primary halide and undergoes S reactions very efficiently.
Step 3: Conclusion.
Thus, the halides that undergo S reactions are Benzyl chloride (B) and n-butyl chloride (D).
Final Answer:

Step 1: Recall the effect of a dielectric.
When a dielectric material is inserted between the plates of a capacitor, it increases the capacitance by a factor of the dielectric constant ( ). For an isolated capacitor, the charge remains constant.
Step 2: Force between the plates.
The force between the plates of a capacitor is given by: When a dielectric is inserted, the electric field between the plates decreases, thus reducing the force between the plates. Step 3: Conclusion.
Thus, the force between the plates will decrease.
Final Answer:

Step 1: Recall the types of radiation.
- Alpha rays ( ): Helium nuclei ( ), which are charged particles. - Beta rays ( ): Electrons ( ) or positrons ( ), which are also charged particles. - Gamma rays ( ): High-energy photons, which are electromagnetic waves.
Step 2: Conclusion.
Gamma rays are the only electromagnetic waves among the given options. They are part of the electromagnetic spectrum, unlike alpha and beta rays, which are particles.
Final Answer:

Step 1: Understanding Barr body.
A Barr body is an inactivated X chromosome found in the nucleus of somatic cells in females.
Step 2: Identifying location.
Since females have two X chromosomes, one becomes inactivated in somatic cells to maintain dosage compensation. Hence, Barr bodies are present in normal female somatic cells.
Final Answer:

Step 1: Recall work function.
The work function ( ) is the minimum energy needed to remove an electron from the surface of a metal. It depends on the metal’s electron affinity. Metals with a low ionization energy have a low work function, while metals with higher ionization energies have higher work functions.
Step 2: Compare the metals.
- Cesium (Cs) has the lowest work function due to its low ionization energy (alkali metal).
- Potassium (K) also has a low work function, but higher than Cs.
- Calcium (Ca) is an alkaline earth metal and has a higher work function than alkali metals.
- Platinum (Pt), a noble metal, has the highest work function due to its stable, tightly bound electrons.
Step 3: Conclusion.
Thus, the order of increasing work function is:
Final Answer:

Step 1: Define isotonic solutions.
Two solutions are isotonic if they have the same osmotic pressure ( ) at a given temperature.
Step 2: Colligative properties.
Osmotic pressure, elevation in boiling point, and depression in freezing point are colligative properties — they depend only on the number of solute particles, not on their nature.
Step 3: Density check.
Density is not a colligative property; it depends on both the solute and solvent type. Thus, isotonic solutions may have different densities.
Final Answer: