Chemistry:2019:CBSE:[All India]: Set-I
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Out of KCl and AgCl, which one shows Schottky defect and why?Marks:1
Schottky defect is shown by ionic compounds having small difference in the size of cations and anions. Out of KCl and AgCl, it is shown by KCl, due to comparable sizes of K+ and Cl– ions.
Why does ZnO appear yellow on heating?Marks:1
When zinc oxide is heated, it loses oxygen and there is an excess of Zn2+ ions. The number of excess Zn2+ ions trapped in the interstitial sites is equal to the number of electrons trapped in neighbouring interstitial sites. The presence of free electrons gives rise to the enhanced electrical conductivity and yellow colour to the crystal.
Arrange the following in decreasing order of basic character:
C6H5NH2, (CH3)3N, C2H5NH2Marks:1
(CH3)3N >C2H5NH2> C6H5NH2
What type of colloid is formed when a solid is dispersed in a liquid? Give an example.Marks:1
Sol is formed when a solid is dispersed in a liquid. Paint is an example of sol.
Out of Chlorobenzene and Cyclohexyl chloride, which one is more reactive towards nucleophilic substitution reaction and why?Marks:1
Out of Chlorobenzene and Cyclohexyl chloride, Cyclohexyl chloride is more reactive towards nucleophilic substitution reaction due to partial double bond character of C-Cl bond in Chlorobenzene which is difficult to break. Also chlorobenzene is resonance stablised.
What is the basic structural difference between starch and cellulose?Marks:1
Starch is a polymer of α- glucose whereas cellulose is a polymer of β- glucose.
Write the products obtained after hydrolysis of DNA.Marks:1
The products of hydrolysis of DNA are as follows:
2-deoxyribose + nitrogen containing heterocyclic base + phosphoric acid
Write balanced chemical equations for the following processes:
(a) Cl2 is passed through slaked lime.
(b) SO2 gas is passed through an aqueous solution of Fe(III) salt.Marks:2
(a) Write two poisonous gases prepared from chlorine gas.
(b) Why does Cu2+ solution give blue colour on reaction with ammonia?Marks:2
(a)Chlorine gas is used in the preparation of poisonous gases such as phosgene (COCl2) and tear gas (CCl3NO2).
(b) When ammonia reacts with Cu2+ solution, blue coloured solution is formed due to the formation of a complex.
(a) Cooking is faster in pressure cooker than in cooking pan.
(b) Red Blood Cells (RBC) shrink when placed in saline water but swell in distilled water.Marks:2
(a) Due to increase in pressure caused by steam inside the cooker, the boiling point of water increases. Therefore, cooking is faster in pressure cooker than in cooking pan.
(b) When RBCs are placed in saline which is a hypertonic salt solution, water moves from inside the cell to the outside by osmosis that causes the cells to shrink. But when RBCs are placed in distilled water which is a hypotonic solution, water moves from outside of the cell to the inside and the cell swells.