Chemistry:2014: CBSE [ All India] :Set-I
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Why is adsorption always exothermic?Marks:1
Adsorption is a surface phenomenon.Adsorbate molecules are held to adsorbent due to attractive interactions. Since energy is always released during attractive interactions, adsorption is always exothermic.
Name the method that is used for refining of nickel.Marks:1
Mond process is used in refining of nickel.
Why does NO2 dimerise?Marks:1
NO2 contains odd number of valence electrons. It dimerises, so that it can have even number of electrons in valence shell and form a more stable N2O4 molecule.
Based on molecular forces, what type of polymer is neoprene?Marks:1
Neoprene is an elastomer.
What are the products of hydrolysis of maltose?Marks:1
Maltose gives two units of -D-glucose on hydrolysis.
Write the structure of 4-chloropentan-2-one.Marks:1
4-Chloropentan-2-one has the following structure:
Identify the chiral molecule in the following pair:
A chiral molecule is the one which has a carbon atom bearing four different groups. In the following pair of molecules, the chiral molecule is:
The conversion of primary aromatic amines into diazonium salts is known as __________ .Marks:1
The conversion of primary aromatic amines into diazonium salts is known as diazotisation.
Write the names of monomers used for getting the following polymers:
(i) The monomers of terylene are ethylene glycol and terephthalic acid.
(ii) The monomers of nylon-6,6 are hexamethylenediamine and adipic acid.
Describe the roles of the following:
(i) SiO2 in the extraction of copper from copper matte
(ii) NaCN in froth floatation processMarks:2
(i) In the extraction of copper from copper matte, SiO2 is used to remove iron oxide as slag.
FeO + SiO2FeSiO3
(ii) In the froth floatation process, NaCN is used as a depressant. During separation of two sulphide ores, it selectively prevents one ore from forming froth. For example, when NaCN is added to ores containing ZnS and Pbs, it allows PbS to come with froth, but prevents ZnS from coming to froth by forming Na2[Zn(CN)4] on reaction with ZnS.