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An element has atomic mass 93 g mol−1 and density 11.5 g cm–3. If the edge length of its unit cell is 300 pm, identify the type of unit cell. (NA = 6.023 × 1023 mol−1)
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Calculate the number of unit cells in 8.1 g of aluminium if it crystallizes in a f.c.c. structure. (Atomic mass of Al = 27 g mol–1)
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Give reason for the following:
Red phosphorus is less reactive than white phosphorus.
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A first order reaction takes 20 minutes for 25% decomposition. Calculate the time when 75% of the reaction will be completed.
(Given : log = 2 = 0·3010, log 3 = 0·4771, log 4 = 0·6021)
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Give reasons for the following :
Aquatic animals are more comfortable in the cold water than in warm water.
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Write the chemical reactions involved in the process of extraction of Gold. Explain the role of dilute NaCN and Zn in this process.
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Write the product when D-glucose reacts with conc. HNO3.
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Give reason (CH3)2NH is more basic than (CH3)3N in an aqueous solution.
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An element 'X' (At. mass = 40 g mol-1) having f.c.c. the structure has unit cell edge length of 400 pm. Calculate the density of 'X' and the number of unit cells in 4 g of 'X'. (NA = 6.022 × 1023 mol-1)
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Arrange the following in the increasing order of their pKb values:
C6H5NH2, C2H5NH2, C6H5NHCH3
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Which allotrope of sulphur is thermally stable at room temperature ?
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Why is Butan-1-ol optically inactive but Butan-2-ol is optically active?
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Draw the geometrical isomers of complex [Pt(en)2Cl2]2+.
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What is the role of dilute NaCN in the extraction of gold ?
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Illustrate the following reactions giving suitable example in each case
Ammonolysis
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Write the structures of main products when benzene diazonium chloride (C6 H5 N+2CI−)C6 H5 N2+CI- reacts with the : HBF4/∆
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Write the structures of main products when benzene diazonium chloride (C6 H5 N+2CI−)C6 H5 N2+CI- reacts with the :Cu/HBr
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Which reducing agent is employed to get copper from the leached low-grade copper ore?
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Glucose on reaction with HI gives n-hexane. What does it suggest about the structure of glucose?
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State Henry's Law. What is the effect of temperature on the solubility of a gas in a liquid?
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