Chemistry Answer the following in brief.

1. The order of a chemical reaction is experimentally determined. Hence, the order can be zero.
2. Molecularity refers to how many reactant molecules are involved in reactions.
3. The number of molecules in any reaction cannot be zero.
   Hence, for a zero-order reaction molecularity can never be equal to zero.

1. Nanotechnology has raised the standard of living but at the same time, it has increased pollution which includes air pollution. The pollution caused by nanotechnology is known as nano pollution. This kind of pollution is very dangerous for living organisms.
2. Nanoparticles can cause lung damage. Inhaled particulate matter may get deposited throughout the human respiratory tract and then in the lungs.
3. The characteristics of nanoparticles that are relevant for health effects are size, chemical composition, and shape.

1. Similar to lanthanoids, they appear silvery-white in colour.
2. These are highly reactive radioactive elements.
3. Except promethium (Pm), all are nonradioactive in nature.
4. They experience decrease in the atomic and ionic radii from actinium (Ac) to lawrencium (Lr), known as actinoid contraction.
5. They usually exhibit +3 oxidation state. Elements of the first half of the series usually exhibit higher oxidation states.

1. in the manufacture of fertilizers. For example, ammonium sulfate, superphosphate, etc.
2. in the manufacture of pigments, paints and dyestuff intermediates.
3. in petroleum refining.
4. in detergent industry.
5. in metallurgy, for cleaning of metals electroplating and galvanising.
6. in storage batteries.
7. as a laboratory reagent.
8. in the manufacture of nitrocellulose products.

1. The process by which a network of cross-links is introduced into an elastomer is called vulcanization.
2. Vulcanization of rubber is carried out to improve the physical properties of natural rubber.
3. The profound effect of vulcanization enhances the properties like tensile strength, stiffness, elasticity, toughness, etc. of natural rubber.
4. Most frequently the used process of vulcanization is sulfur vulcanization. Sulfur forms crosslinks between polyisoprene chains which results in improved properties of natural rubber.

1. Primary structure of proteins is the sequence of constituent α-amino acid residues linked by peptide bonds.
2. Any change in the sequence of amino acid residues results in a different protein.
3. Primary structure of proteins is represented by writing the three-letter symbols of amino acid residues as per their sequence in the concerned protein.
4. The symbols are separated by dashes. According to the convention, the N-terminal amino acid residue is written at the left end and the C-terminal amino acid residue at the right end.

1. Natural polymers: The polymers obtained from natural source are said to be natural polymers.
   e.g. cotton and linen.
   Natural polymers are further subdivided into two types: Plant polymer and animal polymers.
2. Synthetic polymers: These polymers are artificially prepared by polymerization of one monomer or copolymerization of two or more monomers.
   e.g. nylon and terylene.
   Synthetic polymers are further divided into three subtypes: fibres, synthetic rubbers, and plastics.
3. Semisynthetic polymers: Polymers which are derived from natural polymers are called semisynthetic polymers. These are also called regenerated fibres.
   e.g. cellulose acetate rayon and cellulose nitrate.

1. Bronze, an alloy of copper and tin is tough, strong, and corrosion-resistant. It is used for making statues, medals, and trophies.
2. Cupra-nickel, an alloy of copper and nickel is used for making machinery parts of marine ships, boats. For example, marine condenser tubes.
3. Stainless steels are used in the construction of the outer fuselage of ultra-high-speed aircraft.
4. Nichrome, an alloy of nickel and chromium in the ratio 80 : 20 has been developed specifically for gas turbine engines.
5. Titanium alloys withstand stress up to high temperatures and are used for ultrahigh-speed flight, fireproof bulkheads, and exhaust shrouds.

e.g. Brass, which is an alloy of copper and zinc.

• The relative strength of reducing agents:

1. The species on the right side of half-reactions are reducing agents.
2. The species appearing at the bottom right side of half-reactions associated with large negative E° values are the effective electron donors. They serve as strong reducing agents.
3. The strength of reducing agents increases from top to bottom as E° values decrease.

• Spontaneity of redox reactions:

1. Spontaneity of redox reactions can be predicted from values of electrode potential in electrochemical series.
2. If the species with a higher E° value is reduced (accepts electrons) and that with a lower E° value is oxidized (donates electrons), then the redox reaction in a galvanic cells is spontaneous.
3. The standard cell potential must be positive for a cell reaction to be spontaneous under the standard conditions.

e.g. Nickel steel, chromium steel, stainless steel etc. All steels have 2% carbon.

1. The chemical equation can be represented as:
   
2. The process involved in the Dow process.
3. Uses of phenols:
   a. Phenol is used in the preparation of phenol-formaldehyde resin. For example, bakelite.
   b. Phenols are used as antiseptic in common products like air fresheners, deodorants, mouthwash, calamine lotions, floor cleaners, etc.

1. They are hard and good conductors of heat and electricity.
2. Their chemical properties are similar to the parent metal.
3. Their melting points are higher than the pure metals.
4. Their densities are less than the parent metal.

1. Nylon 6, 6 is a linear condensation polymer with high molecular mass (12000 u to 50000 u).
2. It possesses high tensile strength.
3. It does not soak in water.

Uses of nylon 6, 6: It is used for

1. making sheets,
2. bristles for brushes,
3. surgical sutures,
4. textile fabrics, etc.

1. Nylon 6, 6 is obtained by polymerization reaction between the monomers adipic acid and hexamethylenediamine.
2. Mixing of the two monomers forms nylon salt, which upon condensation polymerization under conditions of high temperature and pressure give the polyamide fibre, nylon 6, 6.

1. Conventionally (+)-glyceraldehyde is represented by the Fischer projection formula having –OH group attached to C-2 on the right side and this configuration is denoted by symbol ‘D’.
2. Similarly, the configuration of (–) glyceraldehyde is denoted by the symbol ‘L’.
3. All the compounds which can be correlated by a series of chemical reactions to (+)-glyceraldehyde are said to have D-configuration.
4. And compounds which are chemically correlated to (–)-glyceraldehyde are said to have L-configuration. This is the system of the relative configuration of chiral compounds.
5. A monosaccharide is assigned D/L configuration on the basis of the configuration of the lowest chiral carbon in its Fischer projection formula.
6. Relative configuration of (+)-glucose with respect to (+)-glyceraldehyde can be drawn as follows:
   

1. HDP is used in the manufacture of toys and other household articles like buckets, dustbins, bottles, pipes, etc.
2. It is used to prepare laboratory wares and other objects where high tensile strength and stiffness is required.

Properties of high-density polyethylene:

1. HDP is crystalline, melting point in the range of 144 - 150 °C.
2. It is much stiffer than LDP and has high tensile strength and hardness.
3. It is more resistant to chemicals than LDP.

• Position of d-block elements in the modern periodic table:

1. The transition elements are placed in the periods 4 to 7 and groups 3 to 12.
2. They constitute 3d, 4d, 5d and 6d series.
3. They are placed at the centre with s block on one side and p block on the other side.
4. The electropositivity, reactivity and other properties show a gradual change from s block to p block through those of the d block elements.

• Position of lanthanoids and actinoids in the modern periodic table:

1. Lanthanoids and actinoids are placed separately at the bottom of the periodic table. They are a subset of 6th and 7th periods.
2. These elements have 1 to 14 electrons in their f orbital, 0 or 1 in the penultimate energy level and 2 electrons in the outermost orbital.

1. The species on the left side of half reactions in electrochemical series are oxidizing agents.
2. E° value measures the strength of the substances as oxidising agents. Larger the E° value greater is the strength of oxidising agent.
3. The species in the top left side of half reactions are strong oxidising agents. As we move down the electrochemical series, E° value and strength of oxidising agents decreases.

1. Revolution in electronics and computing.
2. Energy sector:
   a. Nanotechnology will make solar power more economical.
   b. Energy storage devices will become more efficient.
3. Medical field:
   a. Manufacturing of smart drugs helps cure faster and without side effects.
   b. Curing of life-threatening diseases like cancer and diabetes.

1. Hexagonal close-packed structure is obtained by stacking two dimensional hexagonal close-packed layers.
2. So, the spheres in the first layer are arranged to form two dimensional hexagonal close packing.
3. The spheres of the second layer are placed in the depressions of the first layer. If the first layer is labelled as ‘A’ layer, the second layer is labelled as ‘B’ layer because the two layers are aligned differently.
4. The spheres of the third layer are aligned with the spheres of the first layer. The resulting pattern of the layers will be ‘ABAB....’. This arrangement results in a hexagonal close-packed (hcp) structure.

1. The fluorine atom has no d-orbitals in its valence shell and therefore, cannot expand its octet. Thus, fluorine is the most electronegative exhibit –1 oxidation state only.
2. Cl, Br, and I exhibit –1, +1, +3, +5, and +7 oxidation states. This is because they are less electronegative than F and possess empty d-orbitals in the valence shell and therefore, can expand the octet.

1. The polymers which have two or more types of repeating units are called copolymers.
2. They are formed by the polymerization of two or more different types of monomers in presence of each other.
3. The different monomer units are randomly sequenced in the copolymer.
   e.g. Buna-S, Buna-N

• Similarities in physical properties:

1. All d block elements are lustrous and shining.

2. They are hard and have a high density.

3. They have high melting and boiling points.

4. They are good electrical and thermal conductors.

5. They have high tensile strength and malleability.

6. They can form alloys with transition and non-transition elements.

7. Many metals and their compounds are paramagnetic.

8. Most of the metals are efficient catalysts.

• Similarities in chemical properties:

1. All d block elements are electropositive metals.
2. They exhibit variable valencies and form coloured salts and complexes.
3. They are good reducing agents.
4. They form insoluble oxides and hydroxides.
5. Iron, cobalt, copper, molybdenum, and zinc are biologically important metals.
6. They catalyse biological reactions.

• Differences:
  Although most properties exhibited by d block elements are similar, the elements of the first row differ from second and third rows in the stabilization of higher oxidation states in their compounds.

1. According to this principle of green chemistry, priority is given for the prevention of waste rather than cleaning up and treating waste after it has been generated.
2. Illustration: To develop zero waste technology (ZWT).
   As per ZWT, in chemical synthesis, the waste products should be zero or minimum.
3. It also aims to use the waste product of one system as the raw material for other systems.
   For example:
   a. Bottom ash of thermal power station can be used as a raw material for cement and brick industry.
   b. Effluent coming out from cleansing of machinery parts may be used as coolant water in a thermal power station.

1. Linear or straight chain polymers: When the monomer molecules are joined together in a linear arrangement the resulting polymer is a straight chain polymer. It is obtained from bifunctional monomers or alkenes.
   e.g. PVC, high-density polythene.
2. Branched chain polymers: Monomers having 3 functional groups or already having side chains give rise to branched chain polymers.
   e.g. Low-density polythene.
3. Three dimensional cross-linked polymers: Third type of arrangement is said to be cross-linked or network polymers where cross-links are produced between linear chains. Cross-linking results from polyfunctional monomers.
   e.g. Bakelite, melamine.

1. Monosaccharides: Monosaccharides are carbohydrates which do not hydrolyse further into smaller units of polyhydroxy aldehydes or ketones.
   e.g. Glucose, fructose, ribose
2. Oligosaccharides: Oligosaccharides are carbohydrates which on hydrolysis yield two to ten units of monosaccharides and accordingly they are further classified as disaccharides, trisaccharides, and so on.
   a. Disaccharides yield two monosaccharide units on hydrolysis.
   e.g. Sucrose
   b. Trisaccharides yield three monosaccharide units on hydrolysis.
   e.g. Raffinose
   c. Tetrasaccharides yield four monosaccharide units on hydrolysis.
   e.g. Stachyose
3. Polysaccharides: Polysaccharides give very large number of monosaccharide units on complete hydrolysis.
   e.g. Starch, glycogen, cellulose