Most important one mark questions chemistry

12th Standard EM

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Chemistry

Use blue pen only
Time : 00:20:00 Hrs
Total Marks : 25

    Part - A

    Answer all the following questions

    25 x 1 = 25
  1. \(\Delta { G }^{ o }\) vs T plot in the Ellingham's diagram slopes downward the reaction.

    (a)

    \(Mg+\cfrac { 1 }{ 2 } { O }_{ 2 }\longrightarrow MgO\)

    (b)

    \(C+\cfrac { 1 }{ 2 } { O }_{ 2 }\longrightarrow CO\)

    (c)

    \(2Ag+\cfrac { 1 }{ 2 } { O }_{ 2 }\longrightarrow { Ag }_{ 2 }O\)

    (d)

    \(2Ag+\cfrac { 1 }{ 2 } { O }_{ 2 }\longrightarrow { Ag }_{ 2 }O\)

  2. Pick out the alloy that contains a non-metal as a constituent in it

    (a)

    Brass

    (b)

    Bronze

    (c)

    Steel

    (d)

    Invar

  3. Ignition mixture used in aluminothermite process is

    (a)

    Cr + AI2O3

    (b)

    Mg + BaO2

    (c)

    AI + Cr2O3

    (d)

    Ba+MgO

  4. Malachite has______ composition.

    (a)

    2CuCO3.Cu(OH)2

    (b)

    2CuCO3.Cu(OH)2

    (c)

    Cu2O

    (d)

    Cu2S

  5. Zinc blende is_________

    (a)

    ZnS

    (b)

    PbS

    (c)

    Ag2S

    (d)

    Cu2S

  6. In acid leaching process. the insoluble sulphide is converted into soluble sulphate and elemental_________

    (a)

    carbon

    (b)

    lead

    (c)

    sulphur

    (d)

    zinc

  7. Sulphide ore is converted to oxide form by using the process_________

    (a)

    Calcination

    (b)

    Roasting

    (c)

    Smelting

    (d)

    Leavhing

  8. Magnetic separation it is based on the difference in the_________ of the ore and the impurities.

    (a)

    magnetic properties

    (b)

    chemical properties

    (c)

    physical properties

    (d)

    melting point

  9. Zinc is extracted from Zinc blende by_________

    (a)

    Carbon reduction process

    (b)

    Nitrogen reduction process

    (c)

    Oxygen reduction process

    (d)

    All of these

  10. \(ZnS+{ 3O }_{ 2 }\overset { \Delta }{ \longrightarrow } 2ZnO+{ 2SO }_{ 2 }\uparrow \) .The above equation is an example for________.

    (a)

    calcination

    (b)

    reduction

    (c)

    roasting

    (d)

    leaching

  11. Gibb's free energy is given by_______

    (a)

    \(\Delta { G }^{ 0 }=-nF{ E }^{ 0 }\)

    (b)

    \(\Delta { G }^{ o }=nF\)

    (c)

    \(\Delta { G }^{ o }=nF{ E }^{ o }\)

    (d)

    \(\Delta { E }^{ o }=-nF{ G }^{ 0 }\)

  12. Na[Ag(CN)2] is _________.

    (a)

    Sodium aurocyanide

    (b)

    Sodium meta aluminate

    (c)

    Aluminosilicate

    (d)

    Sodium dicyano argentate

  13. \({ Zn }_{ (s) }+2\left[ Au(CN)_{ 2 } \right] ^{ - }_{ (aq) }\longrightarrow \left[ Zn(CN)_{ 4 } \right] ^{ 2- }_{ (aq) }+2Au{ { u }_{ (s) } }\) In the above equation) the oxidation state of metallic;gold is_______

    (a)

    1

    (b)

    0

    (c)

    +2

    (d)

    -2

  14. Semiconductors are purified by_______method.

    (a)

    Zone refining

    (b)

    Electrolytic refining

    (c)

    Mond's process

    (d)

    Beisemerisation

  15. Magnesite is_________

    (a)

    Magnesium oxide

    (b)

    Magnesium carbonate

    (c)

    Magnesium sulphate

    (d)

    Magnesium chloride

  16. The following set of reaction is used for refming titanium. This method is known as___________
    \({ Ti }_{ (g) }+{ 2I }_{ 2(s) }\longrightarrow { TiI }_{ 4 }\left( vapour \right) \)
    \({ Til }_{ 4 }(va[pour)\longrightarrow Ti_{ (g) }+{ 2I }_{ 2(s) }\)

    (a)

    Hall Herold process

    (b)

    Mond process

    (c)

    Van-Arkel process

    (d)

    Alumino thermic process

  17. In the metallurgy of iron) limestone is added to coke. Which acts as a_______

    (a)

    Reducing agent

    (b)

    Oxidising agent

    (c)

    Slag

    (d)

    Flux

  18. A mixture containing sulphides of copper and iron is called______

    (a)

    mineral

    (b)

    ore

    (c)

    matte

    (d)

    matrix

  19. Cinnabar is the sulphide ore of_________metal.

    (a)

    Zn

    (b)

    Pb

    (c)

    Hg

    (d)

    Ag

  20. The percentage of carbon in high carbon steel is_________

    (a)

    0.5 - 1%

    (b)

    0.15 - 1.5%

    (c)

    0.15 - 1.5%

    (d)

    0.15 - 0.3%

  21. Froth floatation process is suitable for concentrating ______ores.

    (a)

    oxide

    (b)

    carbonate

    (c)

    sulphide

    (d)

    halide

  22. Steelis an alloy of___________

    (a)

    iron and carbon

    (b)

    iron and calcium

    (c)

    copper and carbon

    (d)

    copper and iron

  23. Metal oxide is converted into metal by the:_______ process.

    (a)

    Calcination

    (b)

    roasting

    (c)

    smelting

    (d)

    beesemerisation

  24. Sodium cyanide solution is used to extract _________from its ores

    (a)

    copper

    (b)

    silver

    (c)

    gold

    (d)

    both (b) and (c)

  25. In the thermite proces__________is used as a reducing agent

    (a)

    AI

    (b)

    CO

    (c)

    C

    (d)

    CO2

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