limited supply

Wrought

iron

CO₂ +H₂

moderate

catalyst

Vinyl chloride

m²s^-1

coloring

True

True

False

True

False

This method is used for concentration of sulphide ores of copper, zinc and lead. In this method, powdered ore is put in a tank full of water. And then, some Pine oil is added to it. In the tank, the particles of sulphide ores wetted by pine oil whereas the gangue (impurities like rock particles, sand, etc.) particles are wetted by water. Then air is passed through this mixture. This results in the agitation of water in tank. Which cause the sulphide ore particles to stick with the oil and rise to the surface in the form of the froth? The gangue particle being heavier remains behind at the bottom of water tank. The froth is separated and concentrated sulphide ore is obtained from it.

Corrosion is an electrochemical process that actually causes some metal to be broken down. It commonly occurs to anode metals when they come into contact with an electrolyte (such as water), oxygen & a cathode(a substance which accepts electrons). A metal’s electrons will flow through the electrolyte and into the cathode, causing the item to wear away. If you add salt to the water the process of corrosion in your item will speed up substantially.

Natural gas, colorless highly flammable gaseous hydrocarbon consisting primarily of methane and ethane. It is a type of petroleum that commonly occurs in association with crude oil and fossil fuel. Natural gas is used for electricity generation, heating and cooking & as a fuel for certain vehicles. It is important as a chemical feedstock in the manufacture of plastic. These gases are often found dissolved in oil at the high pressures existing in reservoir. It often considered to be the gaseous phase of the crude oil & usually contains some light liquid such as propane and butane.

Viscosity:- It is quantity that shows resistance to path of fluids flow. Fluid’s resist the relative motion of immersed objects through them as well as to the motion of layers with various velocities within them. It is represented by ɳ.  Viscosity of liquids decreases with increasing temperature. Increase in temperature reduces the cohesive forces between the molecules of liquid and hence the viscosity decrease with temperature.

Pigments:- Prime pigments to imparts color & opacity
Winder:- A polymer often referred to as resin, forming a motion to hold the pigment in place
Extender:- Larger pigment particles added to improve adhesion.
Solvent:- Either an organic solvent or water is used to reduce the viscosity of the paint for better application.
Additives:- used to modify the properties of the liquid paint or dry film.
Function of Drying oil:- The most important and unique function of oil paints is the thin coating of oil on each particle of pigment.  The coating consists of a drying oil such as linseed or poppy oil. The oil dries through oxidation; a chemical reaction between the oxygen in the air and the oil, and through evaporation. 

Glass is an amorphous solid. Glass does not have any crystalline structure. They usually are hard and brittle solids. Glass is the name given to any amorphous solid that displays a “glass transition” near its melting point. This is related to the glass transition temperature, which is the temperature where an amorphous solid becomes soft near its melting point or a liquid becomes brittle near its freezing point.
Composition of glass:- 
                   Silicon dioxide (SiO₂)
                   Limestone Or calcium carbonate (CaCO₃)
                   Sodium carbonate (Na₂CO₃)

The Pilling-Bedworth ratio (P-B ratio), in terms of metal corrosion, is the ratio of elementary cell volume of metal oxide to the elementary cell. Volume of the equivalent metal where the oxide has been created. By using the P-B ratio, it can be determined if it is possible for the metal to undergo passivation in the presence of dry air building a protective oxide film. The metal oxide P-B ratio can be best described as the ratio of the metal oxide volume produced by the oxygen and metal reaction to the consumed value of metal. This can be further defined in the equation:
RPB = V_oxide / V_metal  = (M_oxide x P_metal) / n x (M_metal x P_oxide)

R_PB = Ratio(Pilling-Bedworth)
M = Molecular or atomic mass
n = Metal atom per one oxide molecule
v = The molar value
P = The density.

Nylon-66 is made or synthesised by acid and hexamethylene diamine. It is a condensation reaction. To make nylon 66 one doesn’t need a catalyst, but acids to catalyse the reaction, and one of the monomers is itself an acid.
REACTION
Uses of Nylon-66:-
1.    It is waterproof in nature so it is used in swimwear.
2.    It is light material so it is also used in parachutes.
3.    It is also used in manufacturing airbags, carpets, ropes, etc.
4.    It is also used to make machine parts.

Characteristics of a good refractory material
(1)    Be infusible at the temperature to which it is liable to be exposed.
(2)    Chemically inert towards corrosive action of gases, metallic liquid & slag.
(3)    Resist the abrasive action of gases, flames, etc.
(4)    Be able to withstand the overlying load of structures at the operating temperature
(5)    No loss in size.
(6)    Expand and contract uniformly, with temperature rise and fall respectively.

Primary pollutants:- It is an air pollutant emitted directly from sources.
For example: oxides of sulphur, oxides of nitrogen, oxides of carbon, etc.
Secondary pollutants:- It is not directly emitted as such but forms when other pollutants (primary) react in the atmosphere.
For example: ground-level ozone, smog and persistent organic pollutants (pops), etc.

The main ores of copper ore chalcopyrite(CuFeS2), chalcocite(Cu2S), bornita(2Cu2S.CuSFeS), diganite(Cu9S5), cuprite(Cu2O). 
Chalcopyrite(CuFeS2) is the main ore of copper which is also known as copper pyrites. It is converted to copper by different method from silicates, carbonate or sulphate ores. The ores typically contain low percentage of copper and have to be concentrated before refining (e.g. via froth flotation).
The Process:- the concentrated ore is heating strongly with silicon dioxide and air or oxygen in a furnace or series of furnaces.
->    The copper (II) ions in the chalcopyrite are reduced further to copper (I) sulphide which is reduced further to copper metal in the final stage.
->    The iron in the chalcopyrite ends up converted into an iron (II) silicate slag which is removed.
->    Most of the sulphur of the chalcopyrite turns into sulphur dioxide gas. This is used to make sulphur dioxide gas. This is used to make sulphuric acid via the contact process.
An overall equation for this series of steps is:-
2CuFeS₂+2SiO₂+4O₂--------------------> Cu₂S+ 2FeSiO₃+3SO₂

The copper(I) sulphide produced is converted to copper with a final blast of air.
Cu₂S+O₂--------------------> 2Cu +SO₂

(a) The process of slowly eating away of the metal due to attack of the moisture & atmospheric gases on the surface of the metal resulting into formation of compound such as oxides, sulphides, carbonates, sulphates is called corrosion.

The phenomenon of corrosion can be described as

At anode:

Fe(s) undergoes oxidation to release electrons

Fe(s)    →     Fe²⁺(aq) + 2e^-

At cathode:

O₂(g) + 4H⁺ + 4e^-        →     2H₂O(e)

Electrons released at anode move to another metal & reduce oxygen in the presence of H+. It is available from H₂CO₃ formed from the dissolution of CO₂ from air into water H+ in water may be available also through dissolution of other acidic oxides from the atmosphere.

Net reaction:

Fe(s) +2H⁺(aq)+1/2 O₂(g) ^-        →      Fe²⁺(aq) + H₂O(g)

Fe2+ again gets oxidised to form rust.

Fe(s) +2H⁺(aq)+1/2 O₂(g) ^-        →      Fe₂O₃(s) + 4H⁺

                                                                                (Rust)

Acid theory of corrosion:- Acid theory suggests that corrosion of metal(iron) is due to the presence of acid around it. According to this theory, iron is corroded by atmospheric CO₂, moisture and oxygen. the corrosion products are the mixture of Fe(HCO₃)₂, Fe(OH)Co₃  & Fe(OH)₃. The chemical reaction suggested are given below:

Fe +2CO₂+H₂O+1/2O₂ ----------------------> Fe(HCO₃)₂

2Fe(HCO₃)₂ +H₂O + 1/2O₂ -------------------> 2Fe(OH)CO₃+ 2CO₂+ 2H₂O

2Fe(OH)CO₃+ 2H₂O---------------> 2Fe(OH)₃+2CO₂

(b)    Advantages:-
(1)    Gaseous fuel is easier to handle than solid fuels.
(2)    Gaseous fuels can be transported easily through pipelines where as solid fuels cannot be transported in this way.
(3)    Liquid and gaseous fuels do not leave any residue after burning.
(4)    Gaseous fuel has higher calorific value than the solid fuel.
(5)    Gaseous fuel produce little or no smoke, whereas most of the solid fuels burns with smoke.

(c)    Anti-knocking compound is that compound which is added to gasoline to eliminate knocking of engine. E.g. Pb(C2H5)4 is good antiknock. Alcohol, ferrocene, toluene, etc. are also anti-knocking agent.

(a)    A superconductor is an element or metallic which when cooled below a certain threshold temperature, the material dramatically closes all electrical resistance. In principle, superconductor can allow electrical current to flow with any energy loss. The type of current is called a super current.
The threshold temperature below which a material transition into a super conductor state is designated as to which stands for critical temperature. Not all materials turn into super conductors & the materials that do each have their own value of Tc.

 Types of super conductors:-
Type I:- Super conductors  acts as conductors at room temperature, but when cooled below Tc, the molecular motion with in the material reduces enough that the flow of current move unimpeded.
Type II:- superconductors are not particularly good conductors at room temperature, the transition to a super conductor state is more gradual than Type I superconductors. The mechanism and physical basis for this change in state is not at present, fully understood Type II superconductors are typically metallic compounds and alloys.

(b)     Varnish is a transparent, hard, protective finish or film. Primarily used in wood finishing but also for other material. Varnish is traditionally a combination of drying oil, a resin & a thinner or a solvent. Varnish finishes are usually glossy but may produce stain.
Characteristics:- 
(1)    It should dry rapidly.
(2)    It should form a hard film on drying.
(3)    It should be durable and weather resistant.
(4)    It should not crack on drying.
(5)    It should not hide the natural grace of the inner surface of timber.
(6)    The color of varnish should not fade away with time.

(c)    The film lubrication is transition region between elastohydrodynamic lubrication and boundary lubrication. A technique of relative optical interference intensity with the resolution of 0.5nm in vertical direction & 1.5µm in the horizontal direction is used in pure rolling process to measure the film thickness with different lubricants speeds, loads and substrate energy.

(a)    (i) PVC (Polyvinyl Chloride):- Vinyl chloride (monomer) and water are introduced into the reactor & a polymerization indicator, along with other additives. It is an endothermic reaction.
Uses:-
(1)    It is used for making sewage pipes.
(2)    It is used for manufacturing window & door frames.
(3)    It is also used for cabling application as a wire insulator.

 (ii) Teflon:- It is plastic like substance which is produced by polymerizing tetrafluoroethylene (CF2=CF2). It is formed when chloroform is treated with the hydrofluoric acid and antimony trifluoride.
                         HF/SbF₃

CHCl₃---------------> CHF₂Cl--------------------> CF₂=CF₂

 n [CF₂=CF₂] -----------> --[--CF₂-CF₂---]—

 Uses:- 
(1)    PTFE is usually used to coat in the non-stick frying pans as it has the ability to resist high temperature.
(2)    It is used as a film interface.
(3)    It is widely used in medical synthesis, test & many more medicines.

(iii) Buna –S:- It is also known as styrene-butadiene. Buna-S is name derived from butadiene & Na- sodium/ natrium & S- styrene. It is derived from two monomers; styrene and butadiene.

[CH₂=CH-CH=CH₂]_n + [CH₃-CH₂]_m  -----à -[-CH2-CH=CH-CH2-CH2-CH2]-

 |                        |                                                          |

Butadiene       Styrene                                                 Buna S                                                                              

Uses:- 
(1)    It is used for manufacture of passenger car tyres, motorcycle tyre, scooter tyre, etc.
(2)    It is also used for manufacturing of conveyor belts, footwears & other goods, etc.

(b)     Air pollution is a mixture of particles & gases that can reach harmful concentration both outside & indoors. Its effects can range from higher disease risks to rising temperature. Smoke, mold, soot, pollen, methane & carbon dioxide are just few examples of common pollutants.
Sources:- Four main types of sources
(i)    Mobile sources; such as cars, buses, planes, trucks & trains.
(ii)    Stationary sources: such as power plants, oil refineries, industrial facilities & factories.
(iii)    Area sources: such as agricultural areas, cities & wood burning fire places.
(iv)    Natural sources: such as wind blown, dust, wild fires & volcanoes.

Prevention:
(i)    Conserve energy at home, at work, everywhere.
(ii)    Consider using the gas logs instead of wood.

(iii)    Reduce the use of private vehicles & use public transport instead.
(iv)    Stop cutting the trees.
(v)    Avoid burning leaves, trash and other material.
(vi)    Reduce the use of fire place & wood stove.

(a)    GCV or HCV =1/100 [ 8080C + 34500(H-O/8)+22400s]
                      = 1/100[8080 x80 +34500 (7-3/8+ 22400 x3.5]
                      =1/100 [646400+228562.50+78400]
                      =1/100[953362.50]
                      = 9533.62 cal/kg

(b)    Addition polymerisation is addition of polymers. The repeating monomers units form a linear of structure depending on the type of monomer. During addition polymerization, the monomer rearranges themselves to form a new structure. But there is no loss of an atom or a molecule. 

Like PVC polymerisation

nH₂C=CHCl   ---à [H2C-CHCl]_n

Condensation polymerisation is that in which two monomer attached & there is loss of any small molecule during the polymerisation. (Small molecule like H₂O, etc.)

            0      0                                                 0      0

n HO- C̎-R- C̎-OH  + nH₂N-R’-NH₂ ---à -[-C̎-R- C̎-NR’H-NH-]_n- +2H₂O

(c) Global Warming:- Scientist interchange the term global warming with climate change. Although temperature rises in certain areas but the ocean current move the heat around in different parts of the globe. As a result of which some regions experience cooler climate and some experience warmer weather. Therefore, climate changes vary in different regions. Hence, the term climate change is generally used by scientists instead of global warming.
 Earth surface has the ability to absorb almost 75% of the entire solar energy. This is responsible for the increase in temperature. However, part of the energy is given back to the atmosphere in the form of radiation. There are certain gases that have the ability to trap heat and restrict the heat from escaping from the atmosphere. These gases are called Greenhouse gases.

Greenhouse effect:- It is a phenomenon by which the radiations comes from the sun is trapped in the Earth’s atmosphere by the greenhouse gases. There greenhouse gases are making layer or blanket around the earth’s surface and trapped by the blanket of greenhouse gases. The main greenhouse gases which cause global warming is Carbon dioxide(CO₂), Ozone(O₃), Chlorofluoro Carbons (CFC), Methane(CH₄), etc.