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The two differences between light waves and sound waves are:

(i) μ = 1/sinc  or sin c = 1/ μ, where 'c' is critical angle and 'μ' is absolute refractive index.

(ii) Critical angle for 'Red ' colour is higher.

Critical angle increases with the increase in wavelength of light, hence, red light having longer wavelength than green light has a higher critical angle.

The process of absorption and then re-emission of light energy is called scattering of light.

(i) The process of absorption and then re-emission of light energy is called scattering of light. 

(ii) Molecules of the smoke are bigger than the wavelength of light is the correct statement.

(i) Scattering is the process of absorption and then re-emission of light energy.

(ii) The smoke from a fire looks white because molecules of the smoke are bigger than wavelength of light, scatter the light off all wavelengths of white light to the same extent.

Therefore, statement-1 is true.

1. 2NH₄Cl + Ca(OH)₂ → CaCl₂ + 2NH₃ + 2H₂O 

2. NH₃ + 3Cl₂ → NCl₃ + 3HCl 

3. 2NH₃ + H₂SO₄ → (NH₄)₂SO₄

Features of Environment Protection Act, 1986 are: 

• To take all necessary measures for protecting quality of environment. 

• Lay down standards for discharge of environmental pollutants. 

• Empower any person to enter, inspect, take samples and test. 

• Establish or recognize environmental laboratories. 

• Lay down safeguards for prevention of accidents and take remedial measures in case of such accidents. 

• Lay down procedures and safeguards for handling hazardous substances

Health insurance is a type of insurance coverage that covers the cost of an insured individual’s medical and surgical expenses. Depending on the type of health insurance coverage, either the insured pays costs out of pocket and receives reimbursement, or the insurer makes payments directly to the health service provider.

Internet fraud is a fraud committed on the Internet, using the Internet and by means of the Internet. Internet fraud is the use of Internet services or software with Internet access to defraud victims or to otherwise take advantage of them. Frequent instances of Internet fraud include business fraud, credit card fraud, internet auction fraud, investment schemes.

Cyber fraud refers to any type of deliberate deception for unfair or unlawful gain that occurs online. The most common form is online credit card theft. Other common forms of monetary cyber fraud include non-delivery of paid products purchased through online auctions and non-delivery of merchandise or software bought online. Cyber fraud also refers to data break-ins, identity theft, and cyber bullying, all of which are seriously damaging. ,

During winter, surrounding temperature is low and there is almost no sweating. So water is not lost by perspiration. Hence water along with waste substances is mainly removed through urine. So we urinate frequently in winter than in summer.

Following are the advantages of electromagnet over permanent magnets.

(i) An electromagnet can produce a strong magnetic field.

(ii) The strength of the magnetic field of an electromagnet can be easily changed by changing current in its solenoid.

(i) The atoms of different elements which have the same mass number 'A', but different atomic number 'Z' are called 'Isobars'.

(ii) ^23₁₁ Na and ^{23 ₁₂}Mg are isobars having same mass number '23' and different atomic numbers

The S.I. unit of energy is joule

1 eV = 1.6 x 10^-19 J

 Velocity ratio is defined as the ratio of the displacement of the effort to the displacement of the load.

Velocity ratio of a machine. 

Velocity ratio will not change for a machine of a given design and it can be defined as the ratio of the displacement of the effort to the displacement of the load (in the same given time).

Given that (x + 2) and (x + 3) are factors of p(x) = x³ + ax + b.

∴ p(- 2) = (- 2)³ + 0(- 2) + b = 0 

⇒ – 8 – 2a + b = 0 => – 2a + b = 8 …….(i) 

And p(- 3) = (- 3)³ + a(- 3) + b = 0 

⇒ – 27 – 3a + b = 0 => – 3a + b = 27 ……..(ii) 

Subtracting (i) from (ii), we obtain 

(-3a 4 – b) – (-2a + b) = 27 – 8 

– 3a + b + 2a – b = 19 

-a = 19 

⇒ a = 19 

From (i), we obtain 

– 2(19) + b = 8 

– 38 + b = 8 

⇒ b = 8 + 38 

⇒ b = 46 

Hence, the values of a and b are a = 19 and b = 46.

(i) Since PQRS is a cyclic quadrilateral 

∠QPS + ∠QRS – 180° 

⇒ 73° + ∠QRS = 180° 

⇒ ∠QRS = 180° – 73° 

∠QRS = 107° 

(ii) Again, ∠PQR + ∠PSR = 180° 

∠PQS + ∠RQS + ∠PSR = 180° 

55° – ∠RQS + 82° = 180° 

∠RQS = 180° – 82° – 55° = 43° 

(iii) In ∆PQS, by using angles sum property of a ∆. 

∠PSQ + ∠SQP + ∠QPS = 180° 

∠PSQ + 55° + 73° = 180° 

∠PSQ = 180° – 55° – 73° 

∠PSQ = 52° 

Now, ∠PRQ = ∠PSQ = 52° [Oop. ∠s of the same segment] 

Hence, ∠QRS = 107°, ∠RQS = 43° and ∠PRQ = 52°

(i)

(ii)

The title is ‘Mother’s tent like bathing suit’. 

On seeing mother clothed in voluminous black costume, Roger the dog is surprised, starts barking wildly but mother sticks to her costume and refuses to give in.

(i) The car went through the wall and Uncle Ken brought it to a halt in the middle of Maharaja‘s lawn. Looking at this, the Maharaja himself came to see. When he saw it was Uncle Ken & he was beamed with pleasure. He exclaimed to Uncle Ken that he was delighted to see his old chap & if he would like to play a game of tennis with him.

(ii) The suitable title for the given extract is ―Everything is possible‖. When we look at the attitude & behavior Uncle Ken he is a person who never loses hope or gives up. Even though he lost his job, he had the willingness to do something & that‘s how he learned driving & thought of another business.

No matter how many obstacles come into his ways he kept going.

WAITING OUTSIDE THE EXAMINATION HALL 

I was waiting outside the examination Hall of Harcourt Butler School, on the first day of our Higher Secondary examination. It was ray first experience of sitting in an exam outside my school. There was a strange feeling. I was apprehensive but not nervous. 

This was the first step in a student's life to enter a bigger life outside his school where he has spent many years preparing himself for this day. Today was English Paper I. It was my favourite subject. 

There were so many other boys from my school as well as some other schools too. Different types of noises were coming from everywhere. Some were frantically checking their notes for a final time before the first bell was to ring. Some were rehearsing lines mutely, but with their lips moving. Some of my classmates were also busy, the same way avoiding the eyes of their friends. Some parents had also come and were seen giving last minute tips to their children.

I stood in a corner, silently, not trying to remember or recollect anything in particular. I was so lost in my own thoughts that I missed the first bell, but suddenly found the other children hurrying towards the exam hall. When I began moving one of my classmates with whom I used to share a desk in class came by and both of us moved to the trail.

At the entrance, a teacher asked for the admit card which we showed and he asked another person to lean us to our designated seats. We were asked to keep any books, notes, mobiles and other things near the done and collect them on our way out. Only pens, pencils and erasers were allowed in the hall.

It was a big hall which could accommodate about 50 boys at a time. There were four rows of single desks in the hall. My seat was in the middle of the second row while my friend was seated in the fourth row.

As we were seated the invigilators started giving us the answer sheets and we were asked to put our name, roll number and subject on the top. This was done, exactly at 9 a.m.. when the question papers were distributed to each. I sat composed and after a few seconds and then opened the paper and started reading it. I was happy. It was an easy paper and I went through it twice, choosing five best questions which I had prepared well. It was a great experience.

I did moderately well in the exams passing with a good second division and scored highest marks in English in my class.

Examinations sap the examinees of energy and make them sleepless at nights. But then, it has not so far been possible to devise a better way of judging their ability. So, they are a necessary evil. 

It is strange that an examinee‘s ability has to be judged in just three hours. Again, there is no better way out. All who study know that they will have to appear in the examination one day. They have had to work hard for months together. As the crucial day comes, they reach the examination hall, prepared for it, some more some less. A few minutes before the start of the examination, I saw a strange scene outside the examination hall. An eerie silence prevails there. The examinees are carrying their books and notes in their hands which they have already mugged up and are trying to make this mugging firmer and firmer in their minds. Most of the examinees are busy in their own work and are not inclined to talk. But a few, sitting or standing in groups of two or three may be seen discussing some points. 

Even the dullest students appear to be great scholars outside the examination hall. They are poring over their books most attentively. Some of them may be thinking of devising means of copying or behaving if they are caught copying. The brilliant students are also busy revising their notes or lessons. But comparatively, they are not so much agitated. They wear cool and balanced looks.

Most of the students reach the examination hall well before time. They look at the notice-board to find out their room and even try to locate their seats. They try to bring to the notice of the superintendent if they find any discrepancy. But a few careless stud dents reach the hall late and enter it in a state of great excitement. Rarely, there may be one or more students who get delayed because of some genuine difficulty. The supervisors generally try to accommodate them. As soon as the bell rings, all the students enter the hall. 

Even I entered the hall at last. Unlike other students, I went inside with all the materials required for the exam & did my prayers. The supervisor gave the answer sheets & question paper and everybody started writing the paper.

Ore of Aluminium is Bauxite Two uses of Aluminium. 

1. In Aircraft industry 

2. In Electrical wires industry

Two methods of water harvesting in India : 

(i) Recharge through trench 

(ii) Collecting of rain water on the roof top and directing to dry tanks. 

Two Objectives of rain water harvesting : 

1. Avoid flooding of roads 

2. Raise ground water table

Advantages of tube wells: 

(i) Tube well can irrigate a larger area. 

(ii) It does not dry up during summers. Disadvantage: It requires electricity for its working.

(i) Two states are Punjab and Haryana. 

(ii) Perennial Canals are popular there because :

1. Rivers here are perennial. 

2. Land is soft and fertile.

Inundation canals are being converted to perennial canals because: 

(i) They provide water only during rainy season. 

(ii) They are solely dependent on rainfall and irrigates higher regions.

Tube Well 

1. It generally irrigates 2 hectares of land per day. 

2. Tube-wells can bring up water or irrigate land quickly with the help of machines.

Ordinary Well

1. It irrigates 0 – 2 hec tares of land per day. 

2. Wells take longer time to irrigate the same area.

Water scarcity occurs because : 

(i) Seasonal rainfall 

(ii) More Demand due to increase in population 

(iii) Increase in urbanisation and Industrial growth.

Tube Wells are extensively used in Uttar Pradesh and Haryana. Because the land is soft to bore and it is a fertile region.

(i) Tube wells are better form of irrigation than the ordinary wells because : 

1. It is capable of irrigating more area, about 2 hectares per day while ordinary wells irrigate 0.2 hectares of area per day. 

2. It is operated by an electric motor or by a diesel engine so water can be easily lifted from greater depths and most suitable in those areas where canal irrigation is not available. 

(ii) The two alternative methods of irrigation are:

1. Sprinkler irrigation. 

2. Trickle-drip irrigation.

1. Maharashtra 

2. Tamil Nadu

Tank irrigation is popular in South India because : 

(i) The hard rocks underlying large areas in the deccan do not allow percolation of water easily. 

(ii) The undulating surface forms natural depressions.

1. To minimize loss of water. Lack of water and minerals in the soil. 

2. This is due to promotion of Social Forestry. 

3. This is due to longer dry season.

1. They are reliable source of irrigation. 

2. They can be easily dug.

Two modern methods of irrigation are : 

1. Perennial canals. 

2. Drip irrigation system. 

They are becoming popular because there is minimum loss of water and can irrigate fields throughout the year.

1. Fertilizer and nutrient loss is minimised. 

2. Loss of water is minimum.

Balanced equations are:

(a) 2Ag₂O + heat →4Ag +O₂

(b) 3MnO₂ + 4Al + heat →3Mn +2Al₂O₃

(c) Cu (OH)₂ + heat →CuO + H₂O

(d) ZnCO₃ + heat → ZnO + CO₂

(e) 2NaNO₃ + heat →2NaNO₂ + O₂

(f) 2Pb(NO₃)₂ + heat →2PbO +4NO₂ +O₂

(g) 2AgNO₃ + heat →2Ag + 2NO₂ +O₂

(h) 2Cu₂O +Cu₂S + heat →6Cu + SO₂

(i) HgS + O₂ + heat →Hg +SO₂

Position in the Periodic Table : Period 3,Group IIIA(13)

The chemical names and formula of the ores of aluminium are:

Red mud consists of ferric oxide, sand etc. left after bauxite dissolves in NaOH forming sodium aluminate and is removed by filtration.

Bauxite ore contains approximately 60% aluminium oxide. The rest being sand, ferric oxide and titanium oxide.

Hydrogen is placed with alkali metals as it has one electron similar to the alkali metals.

(a) Alkali metals: They are placed in IA group, the first column on the left of the periodic table.

(b) Alkaline earth metal: They are placed in IIA group, the second column on the left of the periodic table.

(c) Iron and Zinc: Fe is placed in VIII group and Cu is placed in IB group.

(d) Aluminium: It is placed in IIIA group present on the right of periodic table.

Economic efficiency: The tax should not prevent the efficient allocation of resources.

Administrative simplicity: The tax should be easy and inexpensive to administer.

Flexibility: The tax system should respond easily to changes in economic conditions.

Transparency: Individuals should be able to ascertain their tax burdens so that burdens can be politically tailored to what society considers desirable.

Fairness: The tax system should be fair in its treatment of different individuals.

Economic services are services rendered to create earning and non-economic services are services which do not create earnings.

A trade union or labour union is an organization of workers that have bonded together to achieve common goals such as better working conditions. The trade union through its leadership, bargains with the employer on behalf of union members and negotiates labour contracts with employers.

When the process of deficit financing is undertaken, the supply of money increases. In fact, the supply of cash money increases. In India, for example, if the Govt, decides to issue new money, it will print one rupee notes and/or issue small coins. This increases the cash money supply. If the Government decides to borrow from the Reserve Bank of India (which is India’s central bank) it transfers its securities to the Reserve Bank. On the weight of securities, the Reserve Bank issues currency notes of Rs 2/- or higher denomination. This is how the Govt, gets the extra money. In both cases, the amount of cash money is the economy and, therefore, the total money supply (i.e. cash plus demand deposits in banks) increases. It means extra purchasing power in the hands of the general people. This may create excess demand conditions in the economy. So there will be upward pressure on the general price level.