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A challenge is an opportunity –

Overcoming a challenge gives an opportunity to go up to a higher level than before.

A Challenge is an opportunity for progress:

 (i) A challenge is just not any problem. We usually call only those difficulties a challenge which are significant and can be overcome. For example Established democracies face the challenge of expansion of democratic principle across the regions which can be overcome by empowering different social groups and local government.

(ii) A challenge is a difficulty that carries an opportunity for progress like the foundational challenge faced by evolving democracies. Once the transition is made to democracy, it opens the opportunity for further progress in democracy.

(iii) So, once we overcome a challenge, we go up to a higher level than before. For instance, democracy after facing the foundational challenge and challenge of expansion, leads to the challenge of deepening. This challenge involves empowering the political institutions like political parties, pressure groups and movement groups.

Consequences of majoritarian policies adopted by Sri Lankan Government were : 

(i) Tamils felt the government was not sensitive about Tamil language and culture because Sinhala was declared the official language. 

(ii) Tamils felt discriminated against securing jobs and education which were given preferentially to the Sinhala speakers. 

(iii) Tamils felt the government was practising religious discrimination because the State fostered Buddhism. Relations between Tamils and Sinhalese became strained.

As the heart muscle contracts and relaxes, the valves open and shut, Iettingblood flows into the ventricles and atria at alternate times. When the left ventricle contracts, the mitral valve closes and the aortic valve opens, so blood flows into the aorta.

Oxygenated blood arrives at the right-hand side of the heart. lt enters the heart through the pulmonary vein. Blood is pumped into the left ventricle. Blood is pumped out of the heart, along with the aorta, to the rest of the body.

Two components of Blood are - Plasma and Blood Corpuscles.

HI is stronger acid then HCl because dissociation energy of H–I bond is less than that of H–Cl.

ZSM–5 an example of shape-selective catalyst.

Second order

The number of atoms in a unit cell of a simple cubic crystal is One atom.

(i) Antibiotics
The chemical substances produced from some micro-organism and are used to inhibit the growth of other microorganism or even kill them are called antibiotics. For example, penicillin, chloramphenicol.

(ii) Antiseptics
Antiseptics are the chemicals which prevent or destroy the growth of the harmful microorganism. For example: Savlon, dettol.

(iii) Analgesics
These are the substances which are used to get relief from pain. For example: Aspirin.

Denaturation of Proteins 

When a protein in its native form, is subjected to a change in temperature or change in pH, the hydrogen bond are disturbed. Due to this, globules unfold and helix get uncoiled and protein loses its biological activity. This is called denaturation of protein. During denaturation 2° and 3° structures are destroyed but 1° structures remain intact, e.g., coagulation of egg white on boiling, curdling of milk, etc.

(i) Cationic detergents: These are quarternary ammonium salts of amines with acetates, chlorides or bromides as anions, e.g., cetyltrimethylammonium bromide.

(ii) Enzymes: Enzymes are globular proteins with high molecular mass ranging from 15,000 to 1,000,000 g mol^-1, and form colloidal solution in water. A number of reactions that occur in the body of animals and plants to maintain the life process are catalysed by enzymes therefore enzymes are termed as biochemical catalysts.

(b) Sweetening agents: These are non-nutritive substances which are used as substitute of sugar in food and beverages, e.g., ortho-sulphobenzimide (saccharin), sucrolose, aspartame, etc.

(i) [Cr(H₂O)₂(C₂O₄)₂]^–

(a) Hybridization — d² sp³

(b) Shape — octahedral
(c) Magnetic behaviour — Paramagnetic

(ii) [Co(NH₃)₂ (en)₂]³⁺

(a) Hybridisation — d² sp³

(b) Shape — Octahedral

(c) Magnetic behaviour — diamagnetic

(i) Tetrachloridocobaltate (II) ion
sp³ hybridisation
Tetrahedral
Paramagnetic

(ii) Tetracyanonickelate (II) ion
dsp² hybridisation
Square plannar
Diamagnetic.

(iii) Diaquadioxalatochromate (III) ion
d²sp³ hybridisation
Octahedral
Paramagnetic.

(i) This is due to smaller size of oxygen the electron cloud is distributed over a small region of space, making electron density high which repels the incoming electrons.
(ii) Because P—P bond is stronger than N—N bond.
(iii) Fluorine never acts as the central atom in polyatomic inter-halogen compounds since it is the most electronegative element of the group.

Emulsion is a colloidal solution in which both the dispersed phase and dispersion medium are liquids e.g. milk, cod liver oil, etc.

Sulphur has higher electron gain enthalpy with negative sign.

The reaction between two water molecules to produce hydronium ion and hydroxide ion is known as autoprotolysis of water. This is self ionization of water.

2H₂​O → H_3​O⁺ + OH⁻

This reaction indicates the amphoteric nature of water. It can act as an acid as well as a base. One water molecule donates electron whereas other water molecule accepts electron.

Aluminium occurs as Al₂O₃.2H₂O

Iron occurs as Fe₂O₃ 

NH₃ < R–NH₂ < R₃N < R₂NH

Molality is the number of moles of solute per thousand grams of solvent whereas molarity is the number of moles of solute dissolved in one litre of solution.

Molality is independent of temperature whereas molarity changes with change in temperature as volume changes with temperature.

Biodegradable detergent are decomposed by the microorganisms whereas non biodegradable detergents do not get decomposed by the microorganisms. Biodegradable detergents posses straight allyl chain, but non biodegradable detergents possess branched allyl chain on allyl benzene sulphonate.

Broad spectrum and narrow spectrum antibiotics.

Both antiseptics and disinfectants are used to kill the microorganisms. Antiseptics are applied on living tissues whereas disinfectants are used on non-living objects.

(i) This is because transition metals have strong metallic bonds as they have large number of unpaired electrons.
(ii) There is a close similarity in physical and chemical properties of the 4d and 5d series of the transition elements much more than expected on the basis of usual family relationship. This is because 5d and 4d series elements have virtually the same atomic and ionic radii due to lanthanide contraction. Due to equality in size of Zr and Hf, Nb and Ta, Mo and W, etc., the two elements of pair have the same properties.
(iii) The members in the actinoid series exhibit larger number of oxidation states than the corresponding members in the lanthanide series due to the fact that the 5f, 6d and 7s levels are of comparable energies.

(i) This is because, transition elements have strong metallic bonds due to presence of large number of unpaired electrons.
(ii) This is because in transition elements incoming electron goes into d-orbitals of inner shell whereas in main group elements, the incoming electron goes to outermost shell.

(i) This is because transition metals have strong metallic bonds as they have a large number of unpaired electrons.
(ii) The catalytic activity of transition metals is attributed to the following reasons:
(a) Because of their variable oxidation states transition metals form unstable intermediate compounds and provide a new path with lower activation energy for the reaction.
(b) In some cases, the transition metal provides a suitable large surface area with free valencies on which reactants are adsorbed.
(iii) This is due to poorer shielding by 5f electrons in actinoids than that by 4f electron in the lanthanoids.

(iv) This is because half filled d-subshell (3d⁵ ) in Mn ²⁺ is more stable.
(v) This is because scandium has partially filled d orbitals in the ground state (3d¹ 4s ² ).

1. Xenon is largest in size among all the noble gas atoms and hence it has lowest ionisation energy, as a result of which most of the compounds are of xenon only.
2. In oxygen there is lone pair-lone pair repulsion, so weaker O-O bond. Also, the single bond between Se-Se is weaker due to larger size of Se-atom. Sulphur of being suitable size makes stronger S-S bond and hence shows maximum catention property.
3. H₂SO₄

The polymerisation process in which there are two or more different monomers combined together to form a polymer is known as copolymerisation.

In binary fission, first the division of nucleus occurs, which is followed by the appearance of a constriction in the cell membrane. The cell membrane grows inward, deepening the constriction and from near the middle of the parent body, two daughter cells get separated.

(i) Resistivity of an alloy is generally higher and it does not oxidize easily. So, the elements of electric heating devices such as bread-toasters and electric iron are made of an alloy rather than of a pure metal.
(ii) In series arrangement, same current will flow through all the appliances which is not required and the equivalent resistance becomes higher, hence the current drawn becomes less.
(iii) They are extremely good conductors having a low value of resistivity.

When the object is at infinity from a convex lens, then the image formed is at focus (on the other side of the lens). The lens with stand is fixed at 5.8cm. The focal length of convex lens is 8 cm. Therefore, he should fix up the screen at 13.8 cm mark on the scale.

When a force conductor carrying current is placed perpendicular to the direction of magnetic field, the magnetic field acting on it is given by Flemings's left hand rule. Since the direction of current is the same as that of the motion of a positive charge, the direction of force acting on it when moving perpendicular to the direction of magnetic field is the same as that acting on a current-carrying conductor placed perpendicular to the direction of magnetic field. Obviously, the force acting on an electron is opposite to that. Therefore in this case it is into the page.

When a conductor carrying current is placed perpendicular to the direction of magnetic field, the magnetic field acting on it is given by Flemings’s left hand rule. Since the direction of current is the same as that of the motion of a positive charge, the direction of force acting on it when moving perpendicular to the direction of magnetic field is the same as that acting on a current-carrying conductor placed perpendicular to the direction of magnetic field. Obviously, the force acting on an electron is opposite to that. Therefore, in this case it is into the page.

The heat from interior of the earth can be utilised as a source of energy under certain favourable conditions that are created by natural processes. This is known as geothermal energy. Molten rocks formed in the deeper hot regions of Earth's crust are pushed upward and trapped in certain regions due to geological changes. These spots are called hot spots. Underground water when comes in contact of hot spots, it gets converted into steam due to heat of molten rocks (magma) and remains trapped between the rocks, at high pressure. This stem can be used to run turbines connected to electric generators

R₁, R₂ and V are connected in parallel. This is because these circuit components have two common points.

Fore brain is the main thinking part of the brain.
Four other major function of forebrain are:
(i) Hearing, smell, sight
(ii) Storing information
(iii) Movement of voluntary muscles
(iv) Sensation of either feeling full or hungry.

(i) Atomic number of A is 16
(ii) A is smaller in size than B. Atomic size decreases in moving from left to right in a period.
(iii) A would be chemically similar to O because Both belong to are of the same group in the periodic table.

(i) When we overeat excess of acid is produced in the stomach which causes burning sensation.
(ii) Washing soda is sodium carbonate decahydrate which when exposed to air loses 10 molecules of water and changes to white powder.
(iii) Sodium chloride is a salt of strong acid HCl and strong base NaOH, so it is neutral. Sodium carbonate is a salt of weak acid H₂CO₃ and strong base NaOH, so it is basic.

He is suffering from myopia Concave lens should be used to correct this defect of vision.

f = 1/P
= 1/(–2.5)m = – 4m

(i) Oviduct / Fallopian tube is the site of fertilisation.
(ii) Ovaries performs production of ova.

Malleability and ductility are two properties. Malleability is the property of the metals to be hammered into thin sheets. Ductility is the ability of the metals to be drawn into thin wires.

The ratio is 1 : 2. Sperms contain either X or Y chromosome whereas an egg will always have an X chromosome.

The heat from interior of the earth can be utilised as a source of energy under certain favourable conditions that are created by natural processes. This is known as geothermal energy. 

Molten rocks formed in the deeper hot regions of Earth’s crust are pushed upward and trapped in certain regions due to geological changes. These spots are called hot spots. Underground water when comes in contact with these hot spots, it gets converted into steam due to heat of molten rocks (magma) and remains trapped between the rocks, at high pressure. This steam, then can be used to run turbines connected to electric generators.

(i) Reliefs that the Consumer court can grant to the customers are: 
(a) To refund the price paid.
(b) To pay punitive damages.
(c) To discontinue the unfair/ restrictive trade practice and not to repeat the same in future.
(d) To pay any amount (not less than 5% of the value of the bottle of water) to be credited to the Consumer Welfare Fund or any other organisation/person, to be utilised in the prescribed manner.
(e) To pay adequate costs to the appropriate party.

(ii) Reliefs that the Consumer court can grant to the customers are:
(a) To remove the defect in engine.
(b) To replace the defective engine with a new one, free from any defect.
(c) To refund the price paid.
(d) To pay punitive damages.
(e) To pay any amount (not less than 5% of the value of the defective engine) to be credited to the Consumer
Welfare Fund or any other organisation/person, to be utilised in the prescribed manner.
(f) To pay adequate costs to the appropriate party.
(iii)Reliefs that the Consumer court can grant to the customers are: 
(a) To remove the defect in electrical heater.
(b) To replace the defective electrical heater with a new one, free from any defect.
(c) To refund the price paid.
(d) To pay a reasonable amount of compensation for any loss or injury suffered by the consumer due to negligence of the opposite party.
(e) To pay punitive damages.
(f) To discontinue the unfair/ restrictive trade practice and not to repeat the same in future.
(g) Not to offer hazardous goodslike defective electrical heater for sale.
(h) To withdraw hazardous goodslike defective electrical heater from sale.
(i) To cease manufacture of hazardous goodslike defective electrical heater.
(j) To pay any amount (not less than 5% of the value of the defective goods) to be credited to the Consumer Welfare Fund or any other organisation/person, to be utilised in the prescribed manner.
(k) To pay adequate costs to the appropriate party.

(i) Reliefs that the Consumer court can grant to the customers are: 
(a) To refund the price paid.
(b) To pay punitive damages.
(c) To discontinue the unfair/ restrictive trade practice and not to repeat the same in future.
(d) To pay any amount (not less than 5% of the value of the book) to be credited to the Consumer Welfare Fund or any other organisation/person, to be utilised in the prescribed manner.
(e) To pay adequate costs to the appropriate party.
(ii) Reliefs that the Consumer court can grant to the customers are:
(a) To remove the defect in engine. 

(b) To replace the defective engine with a new one, free from any defect.
(c) To refund the price paid.
(d) To pay punitive damages.
(e) To pay any amount (not less than 5% of the value of the defective engine) to be credited to the Consumer
Welfare Fund or any other organisation/person, to be utilised in the prescribed manner.
(f) To pay adequate costs to the appropriate party.
(iii)Reliefs that the Consumer court can grant to the customers are:
(a) To remove the defect in electrical iron.
(b) To replace the defective electrical iron with a new one, free from any defect.
(c) To refund the price paid.
(d) To pay a reasonable amount of compensation for any loss or injury suffered by the consumer due to negligence of the opposite party.
(e) To pay punitive damages.
(f) To discontinue the unfair/ restrictive trade practice and not to repeat the same in future.
(g) Not to offer hazardous goods like defective electrical iron for sale.
(h) To withdraw hazardous goods like defective electrical iron from sale.
(i) To cease manufacture of hazardous goods like defective electrical iron.
(j) To pay any amount (not less than 5% of the value of the defective goods) to be credited to the Consumer Welfare Fund or any other organisation/person, to be utilised in the prescribed manner.
(k) To pay adequate costs to the appropriate party.