Chemistry
Previous year question paper with solutions for Chemistry Dec-2017
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Question paper 1
SECTION-A
Q1. Fill in the blanks.
i. The combing capacity of an element is called its _________
Answer:
Valency
ii. Horizontal rows in periodic table are called ____________
Answer:
periods
iii. Negatively charged ions are called __________
Answer:
Anion
iv. Volume of 1 mole of a substance is called_______
Answer:
22.4L
v. M shell has _________ sub-shells.
Answer:
3(3s,3p,3d)
vi. Hard water is not used in boilers for raising steam because is forms ________and __________.
Answer:
Calcium and magnesium salt of fatty acids
vii. Any substance which has a tendency o donate a proton is called__________.
Answer:
Base
Q2. Choose the correct answer.
i) Isotopes of the same elements have
(a) Same no. of neutrons (b) same atomic mass
(c) Different chemical properties (d) same no. of protons
Answer:
(d) same number of protons
ii) Carbon in ethylene involves the hybridization
(a) Sp3 (b) sp2 (c) sp (d) dsp2
Answer:
(b) sp2
iii) Oxidation no. of Mn in kMno4 is
(a) +1 (b) +7 (c) +5 (d) +3
Answer:
(b) +7
iv) The general formula of aldehyde is
(a) RCOOR` (b) ROR` (c) RCHO (d) RCOOH
Answer:
(c) RCHO
v) On diluting of buffer solution, its pH
(a) Increasing (b) decreasing (c) remain same (d) May increase or decrease depend on type of buffer
Answer:
(c) remain same
vi) An oxidizing agents is a substance which can
(a) Lose electrons (b) gain electrons (c) undergo increasing in oxidation number
(d) Take part in the reaction as non-metal elements
Answer:
(b) gain electrons
vii) The tetravalency of carbon is shown by the electronic configuration-
(a) 1s2, 2s2, 2p2 (b) is2, 2s2, 2px1, 2py1
(c) 1s2, 2s2, 2px2, 2py0 (d)1s2,2s2,2px2,2y0
(e) 1s2,2s1,2px1,2py1,2pz1
Answer:
(e) 1s2,2s1,2px1,2py1,2pz1
SECTION-B
Q3. Attempt any ten questions.
a. Write the dimensional formula of velocity, pressure and work.
Answer:
Dimensional formula is helpful in finding units from one system to another of the physical quantity.
Velocity is displacement time i.e. units = ms-1
Dimensional formula = [M0L1T-1]
Pressure is equal to mass x acceleration/ area
i.e. [ML-1T-2]
Work is Force x Displacement
i.e. [ML2T-2]
b. Define the terms wavelength, wave number and frequency.
Answer:
Wavelength is a property of a wave that is the distance between the identical points between two successive waves.
Wave is defined as the number of wavelengths per unit distance is represented by
λ is the wavelengthFrequency: It describes the number of waves that pass z fixed place in a given amount of time
= 
c = speed of lightc. What are magic numbers?
Answer:
The protons and neutrons inside the atomic nucleus exhibit shell structure in a manner similar to electrons in an atom. For naturally stable nuclei these nuclear shells fill completely when the number of protons or the number of neutrons is equal to the magic numbers i.e. 2,8,20,50,82 or 126.
d. Give the comparison of covalent and metallic bond.
Answer:
(i) Both covalent and metallic bonds are strong bonds
(ii) Both are primary bonds
(iii) Both bonds result in the formation of complex structures
(iv) the formation of both covalent and metallic bonds result in the formation of more stable compound than the original
(v) compounds with covalent and metallic bonds are insoluble in polar solvents.e. Why hardness is expressed in term of calcium carbonate equivalent?
Answer:
Hard water contains carbonates, chlorides, sulphides of calcium, magnesium, etc. From all of them, the molecular mass of calcium carbonate is 100. Measuring hardness requires one standard value, as a constant to associate with.
Hence the hardness of water is measured in terms of CaCO3 as it would be easier to associate values with respect to 100 as compared to molecular masses of other hardness causing agents.f. Write in brief about potable water.
Answer:
Potable water simply means that is safe to drink and it is becoming scarcer in the world i.e. lack of access to fresh potable water. The amount of drinking water required varies to depend on physical activity, age, health issues and environmental conditions. Potable water like every other substance contains small amounts of bacteria. Most of these bacterias are common ones and they are generally not harmful. Chlorine is usually added to drinking water to prevent bacterial growth while the water streams through pipelines.
g. Explain isothermal and adiabatic process.
Answer:
Isothermal and adiabatic processes are the common terms of thermodynamic while discussing the energy variation in form of heat. In isothermal “iso” means equal and “thermal” means the temperature. Which means the temperature of the system remains constant. The transfer of the heat in or out of the system happens so slowly that thermal equilibrium is maintained. During isothermal process, there is a change in internal energy, heat and work through the temperature remains the same.
An adiabatic process is a thermodynamic process in which there is no heat transfer, into or out of the system and generally obtained by surroundings. The entire system with a strongly insulating material. In this process transfer of energy to or from the system in the form of work only.h. State the first law of thermodynamics.
Answer:
The first law of thermodynamics states that “the total energy of system & its surroundings remain constant” i.e. the change in the energy of a system equals the heat flow in the system from the surroundings Minus the work done by the system on the surroundings”.
Mathematically,
?U = dQ - dWi. How will you define indicator, titration, and endpoint?
Answer:
Indicator:- An indicator is a substance that undergoes a distinct observable change when condition in its solution change. This could be a color change, precipitate formation, bubble formation, temperature change or other measurable quantity. Some commonly used indicators are Blue Litmus solution, Red litmus Solution, Methyl Orange, Phenolphthalein, etc.
Titration:- A titration is a technique when a solution of known concentration is used to determine the concentration of an unknown solution. Typically, the titrant is added from a burette to known of the analytic the reaction is complete.
Endpoint:- The endpoint refers to the point at which the indicator changes color in a titration.
j. Explain electrolytes and non- electrolytes.
Answer:
Electrolyte:- An electrolyte is any salt or ionisable molecule that when dissolved in solution will give that solution the ability to conduct electricity. This is because when a salt dissolves, its dissociated ions can move freely in solution allowing a charge to flow. E.g. table salt is an electrolyte.
Non-electrolyte:- These are compounds that do not ionize at all in solution. As a result, solutions containing non-electrolytes will not conduct electricity. Typically, non-electrolyte are primarily held together by covalent rather than ionic bond. E.g. glucose is non-electrolyte.
k. Give the difference between direct and in-direct redox reactions.
Answer:
Direct Redox Reaction
Indirect Redox Reaction
In which the oxidation amd reduction reactions take place in the same vessel.
Oxidation and reduction take place in different vessel.
The transference of electron occur directly in the solution.
The transference of electrons takes place through connecting wires.
Energy is released in the form of heat.
Most of energy is released in the form of electrical energy.
l. Explain (i) Position isomerism (ii) functional isomerism, giving one example of each.
Answer:
Position Isomerism:- positional isomerism have the same carbon skeleton and the same functional groups but differ from each other in location of the functional groups.
Functional Isomerism:- Functional isomerism have the same molecular formula but different functional group in the given molecule.
Question paper 2
SECTION-A
Q1. Fill in the blanks.
a. Slag is a product of ___________.
Answer:
Flux+ impurity
b. Bronze is an alloy of copper and ___________
Answer:
Tin
c. Water gas is a mixture of hydrogen and ____________
Answer:
Carbon monoxide
d. Galvanizing is the process of depositing __________on ions.
Answer:
Zinc coating
e. Main hydrocarbon of biogas is ______________
Answer:
Methane (CH4)
f. The velocity of grease is __________ than of olive oil.
Answer:
Less
g. In paint, gypsum is used as ___________.
Answer:
Extender
h. The monomer of PVC is _________.
Answer:
Vinyl chloride
i. Least polluting car fuel is _______
Answer:
Compressed natural gas (CNG)
j. The unit of intensity of sound is _________________
Answer:
Decibel (db)
Q2. State True and False.
i. Brass is a non-ferrous alloy.
Answer:
True
ii. A good fuel has low calorific value.
Answer:
False
iii. Volatility of a lubricant should be low.
Answer:
True
iv. Fibres are weaker than elastomers.
Answer:
True
v. Chloromethane is the monomer of PVC.
Answer:
False
SECTION-B
Q3. Attempt any six questions.
a. Explain Froth floation process for the concentration of sulphide ore.
Answer:
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.
b. Write a short note on metal cladding and metal spraying.
Answer:
Metal cladding is a type of protective coating, where the protective metal such as metal powder or foil is bonded to a sub state by applying heat and/or pressure. The study of metal cladding is significant because this method of corrosion protection and wear protection is generally very reliable and cost effective.
Metal spraying is a process for covering a surface with a metallic coating using a spray of molten particle. This process can also be labelled with a more general term ‘thermal spraying’.c. What is a producer gas? Give its composition and uses.
Answer:
Producer gas is a mixture of flammable gases (principally CO2 and H2) and non-flammable gases(N2 and CO2) made by the partial combustion of carbonaceous substances, usually coal, an atmosphere of air and steam. Producer gas has lower heating value than other gaseous fuels, but it can be manufactured with relatively simple equipment; it is used mainly as a fuel in large industrial furnaces.
CompositionCO2, O2, CO, H2, CH4, N2
Uses:-
Producer gas was used primarily as an industrial fuel for iron & steel. Manufacturing such as firing coke ovens & blast furnaces, cement & ceramic kilns, or for mechanical power through gas engines.d. What are functions of lubricants?
Answer:
Uses of Lubricants:-
(i) A lubricant reduces friction & prevents heating.
(ii) It is used for load balancing.
(iii) Long term use of systems may lead to corrosion, therefore, lubricant is used for cleaning it.
(iv) It is used for sealing the macro gaps between the systems.
(v) It is used for rust prevention.e. Difference between thermoplastic and thermosetting plastics?
Answer:
S. No
Thermoplastics
Thermosetting plastics
1
It can be synthesised by the process called addition polymerisation.
It can be synthesised by condensation polymerisation.
2
These have secondary bonds between molecular chains.
These have primary bonds between molecular chains and held together by strong cross links.
3
These have low melting points.
These have high melting points.
4
They have low tensile strength.
They have high tensile strength.
5
They are low in molecular weight
They are high in molecular weight
f. What are the applications of polymers?
Answer:
Applications of polymers:-
(1) Polymers are used in aerospace & aircraft.
(2) Polymers are used in biomedical like in drug delivery system, biosensor devices, tissue engineering and in other systems.
(3) They are used in fibers, coatings, rubbers, sealing material, solvents & adhesive resins.
(4) They are also used in holography.
(5) They are used in making bulletproof & fire resistant jackets.g. What are main sources of air pollution?
Answer:
Main sources of air pollution:-
(1) Burning of fossil fuels in electricity generation, transport, industry and house hold.
(2) Industrial processes & solvent use for eg. In chemical & mining industries.
(3) By agriculture.
(4) Natural sources including volcano eruptions, windblown dust & emission of volatile organic compounds from plastics.h. Define erosion. How it is different from corrosion?
Answer:
Erosion is the process that describes continuous physical & chemical events which cause the soil & rocks on earth surface to loosen & make the new location.
Both corrosion & erosion happens due to certain external actions on a surface.
Corrosion means the destruction of materials through chemical reactions & erosion means carrying away the top soil from the surface of the earth.SECTION-C
Q4. Attempt any five questions.
i. Describe the composition and uses of bronze and gun metal
Answer:
(1) Bronze is one of the earliest metals known to man. It is defined as an alloy made of copper and another metal, usually tin. Compositions vary but most modern bronze is 88 % copper (Cu) & 12 % tin (Sn). Bronze may also contain Manganese (Mn), aluminium (Al), Nickel (Ni), Phosphorous (P), Silicon (Si), Arsenic (As) or Zinc (Zn).
Uses:-
i) Bronze is used in ship propellers & submerged bearings owing to the combination of toughness & resistance to salt water corrosion.
ii) Phosphor bronze is particularly suited to bearing clips, electrical connections & springs.
iii) It is used to make hammers wrenches & other double tools to be used in explosive atmosphere or in the presence of flammable vapours.
iv) It is preferred metal for top quality bells.
v) It is used in manufacture of various types of metals.
vi) It is used in furniture hardware.(2) Gun Metal:- It is occasionally called red brass in the US. It is an alloy made from Copper (Cu), Zinc (Zn)& Tin (Sn). Aside from its basic constituents modified forms may have nickel & lead which are classified as nickel gunmetal & leaded gunmetal. Chemical composition of gun metal is 88 % copper, 10 Tin & 2 % Zinc.
Uses:
i) It is used in manufacturing of pipe fitting, Valves & pumps.
ii) It is used for making statues.
iii) Bearings, where speeds & load are moderate, are manufactured from gunmetal & used in machinery.ii. Explain electro chemical theory of corrosion.
Answer:
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)
iii. What are fuels? Give the characteristics of good fuel.
Answer:
Fuel:- Fuel is any substance that can provide heat and produce energy when it is burnt. This energy that releases is generally in the form of chemical energy or heat energy. The recent invention of nuclear technology means now even nuclear energy may be released due to nuclear fission or fusion.
The heat energy that fuels release is used for various purpose such as cooking, in heaters and for many other purposes. At other times we use an engine to convert this heat into mechanical energy like when we use petrol to run our cars.
Characteristics of a good fuel:-
1) It is less expensive.
2) It does not leave behind any undesirable substance.
3) It can be transported easily.
4) It is readily available.
5) It burns easily at moderate rate.
6) It has high calorific value.iv. Define fire point, flash point, viscosity, viscosity index, cloud point and pour point.
Answer:
Fire point:- It is the lowest point at which a volatile combustible substance continues to burn in the air after its vapors have been ignited as when heating is continued after the flash point has been determined.
Flash point:- The temperature at which fuel oil gives off vapour that flashes when exposed to an open flame.
Viscosity:- It is the quantity that describes a fluid’s resistance to flow. Fluids resist the relative motion of immersed objects through them as well as to the motion of layers with differing velocities within them it is represented by ? (‘eta’). Which is equal to the ratio of shearing stress (F/A) to the velocity gradient (
) in a fluid.i.e.
Viscosity index:- temperature plays an important role in a fluid’s viscosity, so the world needed a way to measure it with change in the temperature. “The viscosity index is a measure of change in viscosity with fluctuations in temperature”. In simpler terms, the viscosity index tells you how well fluid can protect its viscosity during change in temperature.
Cloud point:- It is temperature above which an aqueous solution of a water-soluble surfactant becomes turbid (opaque).
Pour point:- It is the temperature at which a liquid becomes semisolid and loses its flowing characteristics.
v. What is glass? Give composition and uses of glass.
Answer:
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)
Uses:-
1. Packaging jars for food, bottles for drinks, etc.)
2. Tableware (drinking glasses, plates, cups, etc.)
3. Housing and buildings (windows, facades, reinforcement structure)
4. Interior design and furniture (mirrors, partitions, lighting, etc.)
5. Appliances and electronics (oven doors, T.V., computer screens, etc.)
6. Automotive and transport
7. Fibre optic cables
8. Medical technology
9. Renewable energy (Solar energy glasses, wind turbines).vi. What are lubricants? How are they classified?
Answer:
Lubricants is a substance which is used to control (more often to reduce) friction and wear of the surfaces in a contact of the bodies in relative motion. A lubricant can be in liquid(oil, water, etc.); solid(graphite, grapheme, etc.); gaseous(air) or even semi-solid (grease) forms.
Classification of lubricants:-
? Liquid lubricants: All liquid lubricants, including minerals, natural or synthetic oil, emulsions, etc.
? Solid lubricants: All lubricants in solid form including powder, coatings and composites. (graphite, grapheme, molybdenum disulphide, etc.)
? Gaseous lubricants: Typically its air, but can be other gas.
? Semi-solid: Greases, generally consists of soap emulsified with mineral or vegetable oil.
Lubricants also classified by their main functions:-
? Anti-wear additives:- Reduces wear by the growth of protective layer on the surfaces.
? Extreme pressure additives:- Protects the components from seizure by the formation of coating on the surface.
? Friction modifiers:- Used to control friction typically made of solid particles.
? Corrosion inhibitors:- Protect the surface from the attack of chemical active substance.vii. Explain green house effect and global warming.
Answer:
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.
viii. Define plastic. Give constituent and applications of plastics.
Answer:
Plastic is any synthetic or semi-synthetic organic polymer. In other words, while other elements may be present, plastic always includes carbon and hydrogen. While plastic may be made from just about any organic polymer. Most industrial plastic is made from petrochemicals. Thermoplastics and thermosetting polymers are the two types of plastic. The name plastic refers to the property of plasticity, which is the ability to deform without breaking.
Constituent of plastic:- these chains are called polymers. This is why many plastics begin with poly such as Polyethylene, Polystyrene, Polypropylene. Polymer often is made of carbon and hydrogen and sometimes oxygen, nitrogen, sulphur, chlorine, fluorine, phosphorous or silicon.
Application of plastic:-
1. Due to its sustainability and durability, it is used in making homes, buildings.
2. It is used in automobile.
3. Plastic packaging helps protect and preserve goods.
4. It is used in safety gears.
5. It is widely used in electronics like in computer, telephones, mobile phones, etc. due to its light weight.