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ISC Class 12 Chemistry Solved Question Paper 2011

Short Answer Type

21. Give two differences between a sigma bond and a pi bond.

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22. What is meant by common ion effect?

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23. Give the conjugate acid and the conjugate base for NH₃

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24.
(i) What is meant by promoter? Give an example.

(ii) The solubility product of BaS04 is 1.5 x 10^-9. Find out its solubility in pure water. [1]

(iii) What is the discociation constant of 0.1M solution of a week add HA which is 4.5% ionized at 20°C

i) The promoter is a substance that increases the activity of the catalyst, for example, Mo act as a promoter in Haber’s process to increase the activity of Fe.

ii)

$BaSO subscript 4 space space minus negative greater than space space Ba to the power of 2 plus end exponent space plus SO subscript 4 superscript 2 minus end superscript 1 space space space space space space space space space space space space space space space space space space space space 0 space space space space space space space space space space space space 0 left parenthesis 1 minus straight S right parenthesis space space space space space space space space space space space space straight S space space space space space space space space space space space space straight S Ksp space equals space left parenthesis Ba to the power of 2 plus end exponent right parenthesis left parenthesis SO subscript 4 superscript 2 minus end superscript right parenthesis Ksp space equals straight S squared straight S equals square root of Ksp space equals space square root of 1.5 space straight x space 10 to the power of negative 9 end exponent end root equals space 3.87 space straight x space 10 to the power of negative 5 end exponent space mol space straight L to the power of negative 1 end exponent iii right parenthesis space Degree space space of space Dissoication space left parenthesis straight alpha right parenthesis space equals space 4.5 space percent sign space equals 0.045 conc. space left parenthesis straight C right parenthesis space equals space 0.1 space straight M space Dissociation space const. space Ka space equals ? straight K subscript straight a space equals space fraction numerator Cα squared over denominator left parenthesis 1 minus straight alpha right parenthesis end fraction space equals space fraction numerator 0.1 space straight x space 0.045 space straight x space 0.045 over denominator left parenthesis 1 minus 0.045 right parenthesis end fraction equals fraction numerator 2.025 space straight x space 10 to the power of negative 4 end exponent over denominator 0.955 end fraction space equals space 2.12 space straight x space 10 to the power of negative 4 end exponent$

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25.

Give the IUPAC names for the following: [2]

(i) Na₃[AlF₃]

(ii) [Co(NH₃)₆]C

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26.

For the complex -ion of [Fe(CN)₆]^-3:

(i) Show the hybridization diagrammatically.

(ii) Is it an inner orbital complex or an outer orbital complex?

(iii) State its magnetic property.

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27.

Give balanced the chemcial equations for the following:

(i) Chlorine gas is passed through cold, dilute NaOH.

(ii) Sulphur dioxide gas is passed through NaOH solution.

(iii) Zinc is added to sodium agrentocyanide solution.

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28. Iron is ferromagnetic in nature. Explain why.

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29.

State the common oxidation state of:

(i) Lanthanides

(ii) Actinides

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30. In a given transition series, there is no significant change in the atomic radii of elements which with an increase in atomic number. Explain why.

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