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Assertion: When cement is mixed with wat...

Assertion: When cement is mixed with water and left as such, it becomes hard mass.
Reason: Setting of cement is exothermic process.

A

If both Assertion & Reason are True & the Reason is a correct explanation of the Assertion

B

If both Assertion & Reason are True but Reason is not a correct explanation of the Assertion

C

If Assertion is True but the Reason is False

D

If both Assertion & Reason are False

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The correct Answer is:
B
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Cement is one of the most important building material of the present time. It is a dirty greyish heavy powder containing calcium aluminates and silicates. The important raw materials neede for the manufacture of cement are limestone, clay and gypsum. the main step in the manufacture of cement is the heating of raw meal or slurru in the rotary kiln at a very high temperature 1400-1600^(@)C . Finally 2% or 3% gypsum is added. When cement is mixed with water and left as such for sometime, it becomes a hard mass. This is known as setting of cement. It is believed that varous aluminates and silicates present in the cement form hydrates with water which seperate in the form of gel. the gel formed start losing water partly by evaporation and partly by forming hydrates with unhydrated constituents. this results in the formation of a hard mass. Setting of cement is

Cement is one of the most important building material of the present time. It is a dirty greyish heavy powder containing calcium aluminates and silicates. The important raw materials neede for the manufacture of cement are limestone, clay and gypsum. the main step in the manufacture of cement is the heating of raw meal or slurru in the rotary kiln at a very high temperature 1400-1600^(@)C . Finally 2% or 3% gypsum is added. When cement is mixed with water and left as such for sometime, it becomes a hard mass. This is known as setting of cement. It is believed that varous aluminates and silicates present in the cement form hydrates with water which seperate in the form of gel. the gel formed start losing water partly by evaporation and partly by forming hydrates with unhydrated constituents. this results in the formation of a hard mass. Portland cement does not contain

Cement is one of the most important building material of the present time. It is a dirty greyish heavy powder containing calcium aluminates and silicates. The important raw materials neede for the manufacture of cement are limestone, clay and gypsum. the main step in the manufacture of cement is the heating of raw meal or slurru in the rotary kiln at a very high temperature 1400-1600^(@)C . Finally 2% or 3% gypsum is added. When cement is mixed with water and left as such for sometime, it becomes a hard mass. This is known as setting of cement. It is believed that varous aluminates and silicates present in the cement form hydrates with water which seperate in the form of gel. the gel formed start losing water partly by evaporation and partly by forming hydrates with unhydrated constituents. this results in the formation of a hard mass. The percentage of lime in portland cement is approximately

Cement is one of the most important building material of the present time. It is a dirty greyish heavy powder containing calcium aluminates and silicates. The important raw materials neede for the manufacture of cement are limestone, clay and gypsum. the main step in the manufacture of cement is the heating of raw meal or slurru in the rotary kiln at a very high temperature 1400-1600^(@)C . Finally 2% or 3% gypsum is added. When cement is mixed with water and left as such for sometime, it becomes a hard mass. This is known as setting of cement. It is believed that varous aluminates and silicates present in the cement form hydrates with water which seperate in the form of gel. the gel formed start losing water partly by evaporation and partly by forming hydrates with unhydrated constituents. this results in the formation of a hard mass. Gypsum is added to portland cement

Cement is one of the most important building material of the present time. It is a dirty greyish heavy powder containing calcium aluminates and silicates. The important raw materials neede for the manufacture of cement are limestone, clay and gypsum. the main step in the manufacture of cement is the heating of raw meal or slurru in the rotary kiln at a very high temperature 1400-1600^(@)C . Finally 2% or 3% gypsum is added. When cement is mixed with water and left as such for sometime, it becomes a hard mass. This is known as setting of cement. It is believed that varous aluminates and silicates present in the cement form hydrates with water which seperate in the form of gel. the gel formed start losing water partly by evaporation and partly by forming hydrates with unhydrated constituents. this results in the formation of a hard mass. Concrete is a mixture of

Assertion : Setting of cement is an endothermic process. Reason : Setting of cement involves hydration and rearrangement of the molecules of calcium aluminates and calcium silicates.

Assertion : When electron and holes combine then this reaction is exothermic . Reason : Hole electron can not combine.

Megnesium oxide when mixed with a satureated solution fo MgCl_(2) , sets to a hard mass known as 'Sorel cement' is formed. The composition of sorel cement is MgCl_(2).nMgO.xH_(2)O . What is the value of n ?

Statement I : During the setting of cement the structure has to be cooled by spraying water. Statement II: The constituents of cement undergo hydration during setting of cement and it is exothermic reaction.

ALLEN-S-BLOCK ELEMENTS -EXERCISE
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  2. Which of the following statement is correct for s-block elements:

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  3. One element which is used in flash light in photography, when heated w...

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  4. The s-block hydride with covalent polymeric structure are

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  5. Assertion: Na(2)O(2) is coloured and paramagnetic Reason: Na(2)O(2) ...

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  6. Assertion: KHCO(3) can not be obtained by solvay process. Reason: KH...

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  7. Assertion: Mg can bum in the atmosphere of N(2). Reason: Mg reacts w...

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  8. Assertion: Li(2)SO(4) do not form double salt like alum. Reason: Ato...

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  9. Assertion: Li and Mg shows similar chemical properties. Reason Li an...

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  10. Assertion: NaCI when exposed in air it becomes wet. Reason: NaCI con...

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  11. Assertion: Lithium is most reducing element. Reason: IP of lithium i...

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  12. Assertion: Lithium is the weakest reducing agent among alkali metals. ...

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  13. Assertion: When cement is mixed with water and left as such, it become...

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  14. Assertion: Beryllium is most reducing s-block element Reason: Hydrat...

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  15. Assertion: Halides of Be dissolve in organic solvents Reason: Atomic...

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  16. Assertion: Be has complex formation tendency Reason: Be is s-block e...

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  17. Assertion: Be exhibit photoelectric effect. Reason: Be has least IP ...

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  18. Assertion: In Down's process CaCI(2) and NaF is added with fused NaCI ...

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  19. Assertion: Chlorides of Li, Be and Mg are covalent in nature Reason:...

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  20. Assertion: Barium is not required for normal biological function in hu...

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