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1. The gas which is evolved at cathode: Hydrogen (H₂). 

2. The gas which is evolved at anode: Oxygen (O₂) 

3. The ratio of H₂ and O₂= 2 : 1.

The water vapour which enters into air through the process of evaporation forms clouds in the sky.

Water: vapour is the gaseous form of water.

Cloud: A cloud is a large collection of very tiny droplets of water or ice crystals.

The water cycle: The circulation of water between the earth surface and air.

The kind of weather condition where rain, snow, sleet or hail fall from the sky is called precipitation.

The circulation of water between the earth surface and air is called the Hydrological cycle or water cycle.

Deforestation and pollution are the main reasons that disturb the water cycle.

(d) Ferrous ferric oxide and hydrogen

1. Efflorescence: Certain hydrates lose water when exposed to air of moderate humidity are called substances. 

2. Deliquescence: Certain water-soluble substances, when exposed to the atmosphere at ordinary temperature, absorb moisture from the atmospheric air to become moist and ultimately dissolved in the absorbed water. Such substances are called deliquescent substances.

(a) Soft water: The water present in different natural sources have different substances dissolved in it. The water drawn from certain sources forms a lather with soap rather easily. Such water is called soft water.

(b) Hard water: Water obtained from various sources does not easily form a lather with soap, rather it forms a white sticky scum or a precipitate. This water is called hard water.

When carbon dioxide dissolves in water carbonic acid is formed. 

CO₂ + H₂O → H₂CO₃ (Carbonic acid) Carbonic acid is present in soft drinks.

When steam is passed over red hot iron hydrogen is liberated along with the formation of ferric oxide. 

3Fe + 4H₂O → Fe ↑ + 4H₂

(a) Water gas

(b) Oxygen

(c) Hydrogen

(d) Carbon dioxide

1. When steam is passed over redhot coke, mixture of carbon monoxide and hydrogen is formed.” 

C + H₂O → CO ↑ + H₂↑ 

2. When steam is passed over red hot silicon, which is a non metal silicon dioxide and hydrogen gas are formed. 

Si + 2H₂O → SiO₂ +2H₂ ↑.

• The soil becomes dry 
• Water level in rivers, lakes, dams etc. may fall Ponds and canals may even dry up 
• The ground water level falls

Due to lots of trees , air at that place contains much more water vapour during winters. These vapours condense on dust or smoke particles forming thick fog.

Correct option is C) Marine life

Water has the power to carry silt or finely divided soil in suspension. This silt gives water its colour in rain-fed tanks. These tanks contain water that is mixed with silt.

में गाद या बहुत बारीक मिट्टी को घोलकर ले जाने की क्षमता होती है। यह गाद वर्षा जल से भरने वाले तालाबों के पानी को वह रंग देता है। इन तालाबों में गादयुक्त जल होता है।

The reasons for water pollution nearby my place are as follows : 

• Dumping of solid waste and chemicals from factories directly into water bodies. 
• Dumping of solid waste from homes into water bodies. 
• By the use of chemical fertilizers, insecticides and other medicines in agriculture. 
• Washing clothes and bathing domestic animals in water bodies. Open defecation. 

Bad-effect : Polluted water is harmful for water organims and plants. It is the cause of many diseases. It has an unfavourable effect on land and water organisms. Itreduces the amount of dissolved oxygen in water which is the cause of death of many water organisms. The dissolved pollutants are also harmful for crops.

Water is physically polluted by mud, garbage, paper, food reciduals etc. Water mixed with industrial chemicals, chemical fertilizers, insectisides have dangerous components which turns the water poisionous.

Correct answer is b. Ocean

Hard water contains calcium and magnesium soluble salts. If it is used in industrial boilers, it forms insoluble salts of calcium and magnesium. They produce scales on the inner walls of the boilers, which reduce heating efficiency. There is a chance of explosion of boilers due to foaming. It also corrodes the boilers.

By civilized forests the writer means man-made forests or jungles, forests planted and controlled by man, in other words, systematic planting of suitable trees. One advantage is that they would check soil erosion. 

Civilized forests से लेखक का आशय मनुष्यों द्वारा निर्मित व नियन्त्रित जंगलों से है, दूसरे शब्दों में व्यवस्थित तरीके से उपयुक्त वृक्षारोपण। इसका एक लाभ है कि ये मिट्टी के कटाव को रोकते हैं।

Elixir is an imaginary liquid which is supposed to confer immortality on man. The writer compares water with elixir because water plays a very important role in sustaining life on this planet. Water is the basis of all animal and plant life on the earth. There is a substantial quantity of water in the body of every animal. In the same way, sufficient moisture in the soil is necessary for vegetation. No physiological activity is possible without water. It also gives beauty to the landscape. It has amazing powers. It has shaped the course of the earth’s history. Life cannot even be imagined in the absence of water. So keeping all these facts in mind, the writer compares water with the elixir. 

अमृत एक काल्पनिक द्रव है जिसे कि मनुष्य को अमरत्व प्रदान करने वाला माना जाता है । लेखक जल की तुलना अमृत से करता है क्योंकि जले इस ग्रह पर जीवन को पोषित करने में बहुत महत्त्वपूर्ण भूमिका निभाता है। जल पृथ्वी पर सब प्रकार के जीव व वनस्पति जीवन का आधार है । प्रत्येक प्राणी के शरीर में जल की काफी बड़ी मात्रा होती है। इसी प्रकार वनस्पति के लिए मिट्टी में पर्याप्त मात्रा में नमी होना आवश्यक है। जल के बिना कोई जैविक गतिविधि सम्भव नहीं है। यह भू-परिदृश्य को सौन्दर्य भी प्रदान करता है। इसमें अद्भुत शक्तियाँ हैं । इसने पृथ्वी के इतिहास की दिशा को आकार दिया है । जल के बिना जीवन की कल्पना भी नहीं की जा सकती है। इस सबको ध्यान में रखते हुए लेखक जल की तुलना अमृत से करता है।

Water is the real elixir of life. All humans, animals and plants have a substantial quantity of water in their bodies. No physiological activity is possible without water. Water is essential for all types of life to survive. Sufficient quantity of moisture is essential in the soil for the vegetation to grow and survive. Life on the earth cannot even be imagined without water. It has played a very significant role in shaping the course of the earth’s history. It is the commonest of all liquids. But it is also the most uncommon by virtue of its amazing properties which are responsible for its unique power to maintain life on the earth. Therefore the writer says that scientific research must address these properties of water more and more. 

जल जीवन का वास्तविक अमृत है। सभी मनुष्यों, पशुओं व पौधों के शरीर में पर्याप्त मात्रा में जल होता है। जल के बिना कोई जैविक गतिविधि सम्भव नहीं है। सभी प्रकार के जीवन के लिए जल आवश्यक है। वनस्पति के उगने व जीवित रहने के लिए मिट्टी में पर्याप्त मात्रा में नमी आवश्यक है। जल के बिना पृथ्वी पर जीवन की कल्पना भी नहीं की जा सकती है। पृथ्वी के इतिहास को दिशा देने में जल ने बहुत महत्त्वपूर्ण भूमिका निभाई है। यह सभी द्रवों में सर्वाधिक साधारण द्रव है। लेकिन अपने आश्चर्यजनक गुणों के कारण यह सर्वाधिक असाधारण द्रव भी है जो पृथ्वी पर जीवन देने हेतु इसे अनोखी शक्ति प्रदान करते हैं। इसलिए लेखक कहता है कि वैज्ञानिक शोध के माध्यम से जल के और अधिक गुणों को जानने की आवश्यकता है।

CAZRI, located at the headquarters in Jodhpur works under Indian Council of Agricultural Research, New Delhi. It works in the direction of improving the fertility level of the soil so that its moisture holding capacity may be enhanced. It also works to increase plant cover, to increase productivity and conserve water. New agricultural techniques have been developed. Land degradation is discouraged and efforts are on to increase groundwater level by using rainwater. It had succeeded in its efforts by increasing forest cover, agricultural development in desert areas and providing new techniques to the inhabitants of desert to face severe drought. All these efforts will certainly bear fruit in the direction of checking the growing desert in our state. 

CAZRI जिसका मुख्यालय जोधपुर में है, नई दिल्ली स्थित भारतीय कृषि व अनुसन्धान परिषद् के तत्वाधान में कार्य करता है। यह संस्थान मिट्टी के उपजाऊपन के स्तर में सुधार की दिशा में कार्य करता है जिससे कि मिट्टी की नमी बनाये रखने की क्षमता में वृद्धि की जा सके। यह वनस्पति आवरण को बढ़ाने, उत्पादन क्षमता बढ़ाने व जल-संरक्षण हेतु भी कार्य करता है। कृषि सम्बन्धी नई तकनीकें विकसित की गई हैं। भूमि की गुणवत्ता को बनाये रखने के प्रयास किए जाते हैं और वर्षाजल को उपयोग में लाकर भूमिगत जलस्तर को बढ़ाने के प्रयास जारी हैं । यह संस्थान वनाच्छादित क्षेत्र में वृद्धि करके, मरुस्थलीय क्षेत्रों में कृषि सम्बन्धी विकास करके एवं मरुस्थल के निवासियों को गम्भीर सूखे का सामना करने के लिए नवीन तकनीक उपलब्ध कराकर अपने प्रयास में सफल रहा है। ये सब प्रयास हमारे राज्य में बढ़ते रेगिस्तान को रोकने में निश्चित रूप से फलीभूत होंगे।

Droplets: A drop or the droplet is a small column of liquid.

1. The heat of the sun causes evaporation of water from the surface of the earth, oceans, lakes, rivers and other water bodies. 

2. Water vapour is also continuously added to the atmosphere through transpiration from the surface of the leaves of trees. 

3. Higher up in the atmosphere, the air is cool.

4. These vapours condense to form tiny droplets of water. 

5. These droplets floating in the air along with the dust particles form clouds. 

6. Warm air carrying clouds rises up. 

7. The water droplets come together to form large water droplets. 

8. The large water droplets become heavy and the air cannot hold them, therefore, they fall as rains.

There are three forms of water in nature. They are Ice (Solid form), Water (Liquid form) arid Water vapour (Gaseous form)

The fruits that contains more water are called juicy fruits. 

Ex : Watermelon, grapes, orange, muskmelon. .

correct option is A) 3/4

correct option is D) Watermelon

The correct answer is D) Distillation.