Tag: importance of water

Questions Related to importance of water

Addition of water to $CoCl _2$ changes colour from blue to:

evs water: a precious resource importance of water let's play with water water and its properties water resources and conservation

  1. red

  2. pink

  3. violet

  4. green

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Correct Option: B

Removal of water from $CuSO _4.5H _2O$ changes colour from blue to:

evs water: a precious resource importance of water let's play with water water and its properties water resources and conservation

  1. black

  2. green

  3. white

  4. brown

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Correct Option: C
Explanation:

The colour of anhydrous copper sulphate is white.

Saline water from the oceans consists of ______ percentage of the total water present on the Earth.

evs water: a precious resource importance of water let's play with water water and its properties water resources and conservation

  1. $92.5$

  2. $93.7$

  3. $99.8$

  4. $79.5$

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Correct Option: B

$H _2S$ reacts with $H _2SO _4$, the product may not be 

evs water: a precious resource importance of water let's play with water water and its properties water resources and conservation

  1. $H _2O$

  2. $SO _2$

  3. $S$

  4. $H _2O _2$

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Correct Option: A

The earth appears blue from outer space because:

evs water: a precious resource importance of water let's play with water water and its properties water resources and conservation

  1. of the forest

  2. of the sky

  3. of the water

  4. all of these

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Correct Option: C
Explanation:

The earth appears blue from outer space because 70% of the earth's surface contains water, i.e., water bodies like oceans, seas, rivers, lakes, etc.

Which property of water is used while washing clothes?

evs water: a precious resource importance of water let's play with water water and its properties water resources and conservation

  1. odour

  2. colour

  3. solubility

  4. surface tension

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Correct Option: D
Explanation:

The property of the surface of a liquid that allows it to resist an external force, due to the cohesive nature of its molecules is called surface tension. while washing clothes, detergents reduce the surface tension of the water molecule which causes the formation of foam and cleaning of clothes. 


Option D is correct. 

A sample of water contains sodium chloride and magnesium chloride. Which of the following is not applicable to this?

evs water: a precious resource importance of water let's play with water water and its properties water resources and conservation

  1. It is hard water because magnesium chloride is dissolved in it.

  2. It is hard water because sodium chloride is dissolved in it.

  3. A is hard water because it given only small amount of froth.

  4. It is a hard water because it leaves solid residue on evaporation which given test for $Mg^{2+}$.

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Correct Option: C
Explanation:

Hard water contains chlorides, carbonates and bicarbonates of sodium and magnesium ions which combine with soap micelles and do not give lather with soap.

Find the number of molecules of water in $CoCl _2$?

evs water: a precious resource importance of water let's play with water water and its properties water resources and conservation

  1. 3

  2. 4

  3. 5

  4. 6

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Correct Option: D
Explanation:

The number of molecules of water in $CoCl _2$ is 6. So the formula becomes $CoCl _2.6H _2O$.

Which of the following does not contain impurities?

evs water: a precious resource importance of water let's play with water water and its properties water resources and conservation

  1. Rain water

  2. Distilled water

  3. Both A and B

  4. None of above

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Correct Option: C
Explanation:

Rain water and distilled water does not contain impurities.

Distilled water is water that has had many of its impurities removed through distillation. Distillation involves boiling the water and then condensing the steam into a clean container.

 Rain is liquid water in the form of droplets that have condensed from atmospheric water vapor and then precipitated, that it become heavy enough to fall under gravity. Rain i
s a major component of the water cycle and is responsible for depositing most of the fresh water on the earth. It does not contain any impurities. 

For $\displaystyle 4{ NH } _{ 3 }\left( g \right) +5{ O } _{ 2 }\left( g \right) \rightarrow 4NO\left( g \right) +6{ H } _{ 2 }O\left( g \right) $, if you begin with 16.00 g ammonia and excess oxygen, how many grams of water will be obtained?

evs water: a precious resource importance of water let's play with water water and its properties water resources and conservation

  1. 2.294

  2. 36.51

  3. 1.409

  4. 25.3

  5. 2.513

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Correct Option: D
Explanation:

The molecular weights of ammonia and water are 17 g/mole and 18 g/mole respectively.
4 moles of ammonia gives 6 moles of water.
$4 \times 17 = 68$ g of ammonia will give $6 \times 18 = 108$ g of water.
16.00 g of ammonia will give $16.00 \times \dfrac {108}{68} = 25.3$ g of water.