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Elements which show properties of both metals and non-metals are called metalloids.

For example: Silicon, Germanium.

The ionization reactions of electrolyte in Hall's process.

1. Cryolite: Na₃AlF₆  ⇌ 3Na⁺ + Al³⁺ + 6F^-

2. Fluorspar: CaF₂  ⇌  Ca²⁺ + 2F^-

3. Alumina: Al₂O₃  ⇌ 2Al³⁺ + 3O^2-

The reaction at the cathode and anode are:

Cathode:

4Al³⁺ + 12e^- → 4Al

Anode:

6O^2- -12e^- → 6[O]

3O + 3O → 3O₂

The anode has to be replaced from time to time as it gets oxidized by the oxygen evolved at the anode.

As aluminium has great affinity for oxygen, so it is stable compound. It is not easily reduced by common reducing agents like carbon, carbon monoxide or hydrogen. Hence, electrolytic reduction is chosen as the method for reducing alumina.

(a) Fe₂O₃

(b) PbO

(c) Mn₂O₇

(d) NO

1.Inundation canal: The canals which are drawn directly from the rivers without making any kind of barrage or dam at their head to regulate the flow of the river and canal. 

2. Rooftop rainwater harvesting: It is a technique through which rainwater is captured from the roof catchments and stored in reservoirs. 

3. Surface water: Water that is on the earth’s surface such as streams, rivers, lakes or reservoir, etc.

1. The South Indian region being rocky is difficult to dig. Most of the South Indian rivers are non perennial. 

2. Water is basic input in agriculture. So conservation of water is must for food security. 

3. Rainfall in India is very uncertain, which increases the element of risk and makes crop production rather difficult.

Two factors for development of tubewell irrigation: 

(i) Cheap supply of Electricity. 

(ii) High underground water label.

1. Punjab is an agriculture state so lot of water is required for irrigation. 

2. Rajasthan is a dry state so irrigation is required to cultivate the crop and drinking.

Irrigation is important to a country like India because rainfall here is seasonal in nature. It is limited to four months of a year. It is also important because some crops require more water than what it is provided by the rainfall therefore we have to depend on irrigation.

(i) The world is in danger of facing a severe water shortage in coming future because : 

1. Most of our surface waters are polluted by industrial waste, sewage etc. 

2. The indiscriminate use of chemicals, fertilizers, pesticides, insecticides, to increase farm productions had led to increasing ground water pollution. 

(ii) One measure the Government should adopt to handle present water crisis is rain water harvesting and recycle and reuse of water.

(i) Well irrigation is still a popular means of irrigation because : 

1. It can supply water whenever and where ever required. 

2. It is also a cheap source of irrigation. 

(ii) Significance of rain water harvesting are : 

(i) Reduce surface run off therefore no flooding of roads. 

(ii) It raises ground water table by adding to ground water reserves. 

(iii) It solve the problem of water scarcity.

Rainfall in India is confined to a short duration of three to four months in the rainy season. India has a long growing period which extends throughout the year. Provision of irrigation can make multicropping possible. However, Kharif crops like rice, jute, etc. need more than 150 cm of regular moisture and can hence be grown in areas of low rainfall with the help of irrigation. Multiple crops of rice can be grown within the duration of one year only with the help of appropriate irrigation. Crops such as Sugarcane require 100-150 cm and are grown in large quantities in Deccan India in areas of low rainfall with the help of irrigation. Cotton is another example of a crop which requires plenty of water during its growth period and hence this crop is largely grown in western and northwestern parts of India with the help of irrigation.

(i) 1.Upper Ganga Canal 2. Lower Ganga Canal 

(ii) Canals can be an effective source of irrigation of low relief, deep fertile soil. 

Canal irrigation is a popular form of irrigation in Uttar Pradesh because :

1. The topography consists of low level deep fertile plains. 

2. Large number of perennial rivers provide constant water supply. 

3. Extensive command area.

Modern methods of irrigation are an improvement over the primitive methods. 

The following two points will highlight the same : 

1. They are perennial and provide regular irrigation. 

2. They are easier to operate.

1. A well is by far the simplest and cheapest source of irrigation and the poor Indian farmers can afford it. 

2. A well is an independent source of irrigation and can be used as and when the necessity arises. Canal irrigation is controlled by other agencies and cannot be used at will. The farmer has to pay no tax for well irrigation unlike canal irrigation.

The modern methods of irrigation are more advantageous than the ancient methods of irrigation because: 

1. It is easy to operate. 

2. They provide irrigation to a much larger area. e.g. Tube wells use electric motors to pump up water and they can irrigate a much larger area than an ordinary well. 

3. Regular irrigation throughout the year e.g. perennial canals.

Forest area can be increased by : 

1. Massive trees plantations. 

2. Vigorous restrictions on the reckless felling of trees. 

3. Much of the area reclaimed from the forest for agriculture should be retired from cultivation and brought back under forest.

(i) Tidal forest. 

(ii) Tropical Evergreen forest. 

(iii) Tropical Dry forest.

(i) Because monsoon are seasonal in nature. 

(ii) Because it prevents the loss of water through evaporation and directly reaches the ground. 

(iii) Because the ground around it suffer from the problem of ‘reh’ or salts in the upper layers of the soil.

(i) (1) Tidal forests—Deltas of the Ganga, Mahanadi, Godavari, Krishna and Kaveri. 

(2) Thorn and Scrub forest—Rajasthan and Gujarat. 

(ii) Thorn and scrub forest are found in the above region because these areas get less than 25 cm of rainfall and average temperature of 25°C-27°C.

Forest are important natural resource because : 

(i) They provide timber, medicinal plants etc. 

(ii) They help in purifying air and giving rain.

The constraints are : 

1. Due to human neglect, large tracts of land of U.P., Punjab and Haryana turned infertile due to salinity or alkalinity of soil. 

2. Due to extensive soil erosion or waterlogging or lack of water, agricultural land of the past had to be abandoned. 

3. Due to unfavorable physiographic position or deficiencies in the soil resulting from faulty agricultural practices, large tracts of land now, can not be used for agriculture.

Tanks are widely used in peninsular plateau because the undulating surface forms natural depressions and the streams and rivers there have water only during rains.

Two advantages of rainwater harvesting: 

(i) It avoids flooding of roads. 

(ii) It raises the.ground water table.

(i) Two industries that use high quantity coal are : 

1. Iron and steel industry 

2. Sugar industry 

(ii) Large coal deposits states : 

In Jharkhand—Jharia 

In West Bengal—Raniganj

Two industrial products for which limestone is used: 

1. Iron and steel industry 

2. Cement industry

(i)  Ventricular systole. 

(ii)  Both ventricles are contracting in this phase, because both bicuspid and tricuspid valves are closed in order to prevent the back flow of blood into auricles and the semilunar valves are open. 

(iii)  1. Pulmonary artery 

2.  Aorta

3.  Pulmonary vein.

4.  Left Auricle

5.  Bicuspid valve (mitral valve)

6.  Right ventricle.

(iv)  ‘1’ – carries deoxygenated blood 

‘2’ --- carries oxygenated blood.

(v) Two (Bicuspid and Tricuspid) valves

(i) Ventricular Systole. 

(ii) Ventricle is contracting because both tricuspid and bicuspid valves are closed whereas both pulmonary semi-lunar and Aortic semilunar valves are open to pump the blood out of the two ventricles.

(iii) 1. Pulmonary artery 

2. Aorta 

3. Bicuspid/Mitral valve. 

4. Aortic semi-lunar valve 

5. Tricuspid values. 

(iv) Oxygenated blood flows through part 2. 

(v) Allow deoxygenated blood to flow from right ventricle to lungs and prevents its back flow. 

(vi) Pericardium.

Five Factors Responsible for the Destruction of the Eco System: 

1. Population Growth: Population is growing rapidly but the land is static, which is a great threat to our eco system. Ibis is resulting in deforestation, destruction of natural resources, soil erosion, falling water table, pollution of water sources and atmosphere. 

2. Transport: More and more road network is being expanded, which is resulting in deforestation, extinction of species, urbanisation etc. 

3. Tourism: With the development of tourism, there is a quest to earn more and more revenue and foreign currency. The virgin areas which are rich in natural resources are exposed for the tourists. This is causing a loss of fresh water and habitats. 

4. Agriculture: In order to cater the needs of over growing population, our farmers are using more and more chemical fertilizers and pesticides to increase their productivity. This is resulting into degradation of soil quality and natural food chain process. 

5. Industrialisation: Increase in the number of industries is a great danger to our eco system. It is resulting into deforestation to get more and more land for industries, contamination of water by industrial wastes, air pollution and sound pollution.

Professional and Social Importance of Human Resources Management: 

Professional Significance: Human Resource Management helps in maximising the working potential of the employees by providing a healthy working environment and opportunities for growth. It enhances better understanding among the people working together which leads to effective team work. It boosts the confidence of the people by placing them at the right place at the right time according to their qualification and work experience. HRM also inculcates a feeling of belonging for the organisation. 

Social Significance: Human Resource Management helps the society by utilising and channelising the manpower in the productive channels. It provides maximum opportunities to enhance the dignity of labour by placing the right person at the right job. HRM also raises the standard of living of the people by increasing the employment opportunities.

Advantages of Radio Services in the form of Advertising Media: 

1. It is convenient for the masses due to its wide coverage. 

2. It is good for rural areas as it can even cover illiterate people and lower income segment. 

3. The frequency of repetition of advertisement is more. 

4. People don’t have to sit and watch the advertisement, they can very easily hear them while working. 

5. With the use of extra audio affects, in the form of music and interactive sessions through phone calls, makes the communication more effective. 

Disadvantages: 

1. There is a lack of selectivity due to availability of selective radio channels in our country. 

2. It is costlier due to limited selectivity. 

3. Industrialisation and other factors makes the sound signal weak which results in poor reception. 

4. It has a short life span and back reference is not possible. 

5. It takes visual impact.

(a) Resistors of 5 Ω and 4 Ω are in series, therefore, their net resistance is Rs = 5 + 4 = 9 Ω. 

Now, this 9 Cl and 3 Ω are in parallel, hence net resistance

R_p=9*3/9+3=18/12=1.5Ω

Now, this is in series with the 8 Cl resistor, hence net resistance of the circuit is RT = 8 + 1.5 = 9. 5 

(b) (i) No, specific heat capacity does not remain the same when it changes from solid to liquid. 

(ii) Let us take the example of water. 

Specific heat capacity of water = 4.2 J kg^-1 K^-1 

and specific heat capacity of ice = 2.1 J kg^-1K^-1 

(c) x < y. This is because coil B has more number of turns. 

(d) (i) Because this occurs at a very high temperature. 

(ii) ³He₂ + ²H₁ → ⁴He₂ + _¹H₁ + Energy
(e) The two ways are 

1. Strong magnet and 

2. High current.

(a) (i) Its focal length increases. 

(ii) Thin lens. 

(b) (i) Ratio of intensities will be 1: 9. 

(ii) Ratio of frequencies will be 1:1. 

(c) (i) Increases. 

(ii) Decreases. 

(d) (i) If a body is made to vibrate with its fundamental frequency by an external source, then the vibrations are called resonant vibrations. 

(ii) Quality. 

(e) No, as it does not possess a helium nucleus.

It was recess time and we all were sitting and talking amongst ourselves about school teachers and friends and movie. Prom the rear end of the class we heard a big noise, two of our classmates Rakshit and Rohan had got into fighting. The reason was the same girls. Argument had started over a girl called Tanvi who was a common friend of theirs and my cousin sister. Tanvi studies in a all-girls school in the tenth class. Rohan and Rakshit, Tanvi, and a number of other friends take maths tuition at the same centre. 

When I heard my sister’s name being called out again and again by Rakshit I went to him and started yelling at him as to why was he fighting over my sister. Rakshit tried to explain to me but I would not hear and blasted at him that he was rude and mean. He was a nasty boy as he was talking ill about Tanvi, my sister. I reeled and reeled at him, without giving a break. When all efforts made by Rakshit to make me listen fell on deaf ears, he walked away in anger.

After sometime I cooled down and stopped shouting. By now the whole class was in uproar some took my side and pointing a finger at Rakshit, while others trying to cool me on Rakshit’s behalf. My close friend Arpita was very upset with the entire scene. She thought I had over-reacted in the whole situation. No sooner she said this, I shouted at her and in anger gave her one tight push that she feel and hurt herself Rohan who was in the midst of all affairs and was silently watching came to me. He told me one by one the entire conversation that took place between him and Rakshit and to my horror I realized Rakshit was nowhere at fault. He was rather defending Tanvi and shouting at Rohan for speaking ill of Tanvi. I was very embarassed by my behaviour and fell guilty of my actions. I was at a loss of words to say sorry to Rakshit. 

I realized that suddenly there was a pin drop silence and as I looked up my friend Rakshit was standing in front of me. Tears welled up in my eyes and I said sorry. He hugged me tight saying no sorry, no thank you in friendship. Again bedlam broke out in class as everyone screamed and yelled in happiness as the differences cleaned up.

Here, ft – 3, 2k + 1 and 4k + 3 are three consecutive terms of an A.P. 

∴ 2k + 1 – (k – 3) = 4k + 3 – (2k + 1) 

⇒ 2k + 1 – k + 3 = 4k + 3 – 2k – 1 

⇒ k + 4 = 2k + 2 

⇒ 2k – k =4 – 2 

⇒ k = 2 

Hence, the value of ft is 2.

(a) HNO₃ is strong oxidizing agent.

(b) NaNO₃ gives NaNO₂ and oxygen on heating.

(c) Constant boiling nitric acid contains 68% nitric acid by weight.

(d) Nitric acid turns yellow solution when exposed to light.

The chemical name of the brown ring is Nitroso ferrous sulphate.

Formula: FeSO₄. NO

Three important uses of Nitric acid and the property of nitric acid involved is:

1. In small quantity — a bluish white ppt is obtained. In excess — deep (inky) blue solution is obtained.

2. Turns to black mass called sugar charcoal. 

3. A reddish brown acidic gas called nitrogen dioxide is obtained. 

4. Pungent smelling basic gas called ammonia is evolved. 

5. Reddish metal copper is obtained.

(a)KNO₃

(b) FeSO₄

1. Barium chloride 

2. Platinum 

3. Coke 

4. Acetylene gas 

5. Bronze

(a) Potassium nitrate

(b) Ammonium nitrate

(c) Lead nitrate

Right hand thumb rule helped to find the direction of magnetic field lines.

In the above picture, we can see boys playing cricket in their locality. It seems a match between two groups from the same area which is also called as ―Gully Cricket‖. 

Unlike every game, cricket has its own plus point and its quite an interesting game. The boys seem to be well trained and interested in the picture. The batsman and the 2 fielders both are playing the game sparingly and with a healthy spirit. 

The image shows that batsman has played a shot and the 2 fielders are trying to save their points by stopping the ball or catch the ball. Like the game is played where every run counts a point, the batsman wants to make run and defends his wicket and that's the reason he is striking the bat upwards in the direction of ball. Overall, it seems to be an interesting match also enjoyed and accompanied by the other boys.

(i) battered - damaged by repeated use

(ii) bused - say to oneself in a thoughtful manner.

(iii) emerged - more out of or away from something & become visible.

(i) Granny had a hope that Uncle Ken would keep his job at Firpo‘s hotel as it was a steady job with a good salary.

(ii) The remark of granny tells us a lot about Uncle Ken that he may not be stable at work or did he create any kind of issue due to which the hotel was closed down as she knows him very well. It clearly shows us that maybe granny wanted to point Uncle Ken that he is trying to be serious about ways & means of earning a living.

(iii) Uncle Ken thought that driving a taxi in Dehra because there was only one taxi in the whole of Dehra so there was a business for another.

(iv) The sentence which tells us that the narrator & his friend were waiting to be invited for a drive in a car is : After tea, uncle ken said, come along, Ruskin hop in & I will give you a ride. Bring Mohan along too.‘ Mohan & I needed no urging. We got into the car beside uncle ken.

(v) Miss Kellner saw Uncle Ken driving through the gate & he nearly ran over a cat. Therefore, she ran indoors when she saw Uncle at the wheel of the car.

(iv) Uncle Ken‘s intention was to take a turn & drive back again at the roundabout.

Plot No.-206,

D.N. Nagar,

Andheri (W),

Mumbai.

08th January 2018

Dear Uncle,

Hello, and how are you? I am sure you would be as good as always. Even I am doing well here.

As you know uncle, Next week is my birthday. I know your gifts are always precious & wonderful. As you were telling me last time when we met that you planning to buy a puppy as my birthday gift. I am eagerly waiting for that gift Uncle. It would be wonderful to get a puppy as a gift on my birthday & I am quite excited for it. Since a long time, I was interested to buy a puppy and you got me here. As you know dogs are one of the faithful pets & also useful for safeguarding I think the puppy is the best option for keeping as a pet. I know keeping pets is not easy as they we have to take good care of them like babies. But I can assure you that I will take good care of this puppy & keep you updated about his activities and my training which I would be providing to that pet. I have a thought to name the pet as ―Tyson‖. I hope you like my choice & I am sure his arrival would cherish all of us.

Give my regards to Aunt & Sunny.

With Love,

ABC.

DAV School,

Plot No.-08,

Majesty Road,

Bandra (W),

Mumbai – 400008

January 08, 2018

The Deputy Commissioner,

Mumbai Police (Traffic),

18, Pali Street,

Mumbai – 400009.

Subject: Heavy & chaotic traffic in a school zone.

Dear Sir,

This letter intends to bring to your kind attention the unimaginable harassment that school students face on Majesty Road due to growing instances of traffic jams. We know that the number of vehicles & commuters on the roads is on the rise & that there is no proportional increase in the number of roads. So, traffic jams are bound to happen.

It stretches one‘s tolerance when drivers show irresponsible behaviour as we have all school going kids along with their parents. As this is school area it is suppose to be a Silence Zone but there is no silence infact its chaos & havoc for all of us. We can see vehicles parked at any corner of the road, drivers getting into ugly arguments, rash driving, etc……

If we arrange proper officials on duty & create awareness among people about traffic rules & regulations this can help us to. Also, appropriate sign boards in the area suggesting people what to do & when can improve the situation & help to resolve traffic problems in the school zone. Because if necessary actions are not taken it can lead to many accidents & serious problems.

We have faith in the Police Department & fully understand our officers. With all due respect to all the officers, I believe that the Police Department will pull up its socks to combat this problem of traffic jams in our school zone.

Thanking you in anticipation,

Yours faithfully,

ABC

(1) beginning

(2) sitting

(3) peeped

(4) had

(5) thought

(6) making

(7) ran

(8) took

(9) looked

1. grazing

2. fishing

3. felt

4. Looking

5. found

6. was

7. ludge

8. nooked