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Environmental Chemistry Complete Notes..

Environmental Chemistry Environmental chemistry: It is the branch of chemistry that deals with the study of various chemical processes taking place in the various segments of the environment. Broadly speaking, it is the study of the sources, transportation, reactions, effects and the ultimate of the chemical species occurring in one or more segments of the environment. Components of Environment : Atmosphere:   This comprises a blanket of gaseous layer around earth. Hydrosphere :  This comprises about 96% of earth’s surface & includes all   sources of water like oceans rivers lakes, glaciers, ground water etc. Lithosphere :  It refers to earth’s solid crust containing the outer mineral cover. It comprises soil, minerals, organic matter etc.  Biosphere:   It refers to the domain of living organism in covalent with atmosphere hydrosphere as well as lithosphere.    Environmental pollution...
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HYDROGEN Test Questions SET:-01




CHEMISTRY - XI

 (HYDROGEN)

Full Marks 35                                                          Time: 1:15 hr                       


MULTIPLE CHOICE QUESTIONS:                                 1X5=5

1. On electrolysis in the molten state, which of the following compounds will give H2 at anode:
(a) NH3
(b) HCl
(c) CaH2
(d) PH3

2. Ordinary hydrogen at room temperature is a mixture of:
(a) 25 % o-Hydrogen + 75% p-Hydrogen.
(b) 50 % o-Hydrogen + 50% p-Hydrogen.
(c) 75 % o-Hydrogen + 25% p-Hydroge.
(d) 1 % o-Hydrogen + 99% p-Hydrogen

3. Which of the following is a correct statement?
(a) H2O2 is a basic in nature.
(b) H2O2 is a planar molecule.
(c) In all reduction reactions where reductant is H2O2, dioxygen is liberated.
(d) H2O2 is more stable than H2O.

4. For softening of water by Calgon’s process, the following chemical is used:
(a) Slaked lime.
(b) Sodium hexametaphosphate.
(c) Sodium-aluminium silicate.
(d) Sodium Carbonate

5. Hydrogen Peroxide is not used as:
(a) A reducing agent.
(b) An oxidizing agent.
(c) Dehydrating agent.
(d) Bleaching agent.

VERY SHORT ANSWER TYPE QUESTIONS:                            1X5=5

6. Why is dihydrogen gas not preferred in balloons?
OR
Why Ice floats on water?

7. Why dihydrogen is less reactive at room Temperature?
OR
Name the classes of hydrides to which H2O, B2H6 and NaH belong.

8. Why H2O2 is used as sewage treatment?

9. What do you mean by ‘demineralized’ water?

10. What do you mean by ‘Hydride Gap’?

SHORT ANSWER TYPE QUESTIONS:                            2X5=10

11. What do you understand by the term ‘auto protolysis of water’? What is its significance?
OR
Why does hard water not form lather with soap?

12. What causes the temporary or permanent Hardness of Water? What happens when temporary Hard Water is boiled? Give the relevant equation.
OR
Why hydrogen peroxide is stored in wax lined bottles?

13. What is the difference between hydrolysis and hydration?

14. Write chemical reaction to show amphoteric nature of Water.

15. Discuss briefly de-mineralisation of water by ion exchange resin.
 OR
Calculate the strength of 5 volume H2O2 solution.

LONG ANSWER TYPE QUESTIONS:                              3X5=15

16. (i) Draw the gas phase and solid phase structure of H2O2.
(ii) H2O2 is a better oxidizing agent than water. Explain.
OR
Arrange the following:
(i) LiH, NaH and CsH in order of increasing ionic character.
(ii) H-H, D-D and F-F in order of increasing bond dissociation enthalpy.
(iii) NaH, MgH2 and H2O in order of increasing reducing power.

17.  Why dilute solution hydrogen peroxide cannot be concentrated by heating? How can a concentrated solution of hydrogen peroxide be obtained?

18. A colourless liquid ‘A’ contains H and O elements only. It decomposes slowly on exposure to light. It is stablished by mixing urea to store in the presence of light.
(i) Suggest possible structure of A.
(ii) Write chemical equations for its decomposition reaction in light.

 19. Explain the following:
(i) Temporary hard water becomes soft on boiling.
(ii) Water can extinguish most fires but not petrol fire.
(iii) Hard water is softened before being used in boilers.

20.  Write Short notes on:
(a) Hydrogenation.
(b) Water-gas Shift reaction.
(c) Fuel Cell.

BY:
Anjani Kumar Singh


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