Q23 of 37 Page 1

After watching a programme on TV about the presence of carcinogens (cancer-causing agents) Potassium bromate and Potassium iodate in bread and other bakery products, Ritu a class XII student decided to aware others about the adverse effects of these carcinogens in foods. She consulted the school principal and requested him to instruct canteen contractor to stop selling sandwiches, pizza, burgers and other bakery products to the students. Principal took an immediate action and instructed the canteen contractor to replace the bakery products with some proteins and vitamins rich food like fruits, salads, sprouts etc. The decision was welcomed by the parents and students.

After reading the above passage, answer the following questions:


(i) What are the values (at least two) displayed by Ritu?


(ii) Which polysaccharide component of carbohydrates is commonly present in bread?


(iii) Write the two types of secondary structure of proteins.


(iv) Give two examples of water-soluble vitamins.

(i) Social Responsibility as a good citizen to let others know the bad effects of bakery products and courage to inform principal and stop the usage of them in school.


(ii) Starch is the polysaccharide component of carbohydrates present in bread. Starch is a polymer of glucose. Starch is a mixture of amylose and amylopectin which are 2 different polymers of glucose.


(iii) α-helix and β-pleated sheet structure.


(iv) B group vitamins like thiamine, riboflavin and vitamin C (ascorbic acid) are water soluble vitamins.


More from this chapter

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21

Give reasons :

(i) Thermal stability decreases from H2O to H2Te.


(ii) Fluoride ion has higher hydration enthalpy than chloride ion.


(iii) Nitrogen does not form pentahalide.

 22

Given reasons :

(i) Acetylation of aniline reduces its activation effect.


(ii) CH3NH2 is more basic than C6H5NH2.


(iii) Although –NH2 is o/p directing group, yet aniline on nitration gives a significant amount of m-nitroaniline.

 24

A. Account for the following:

(i) Transition metals form a large number of complex compounds.


(ii) The lowest oxide of transition metal is basic whereas the highest oxide is amphoteric or acidic.


(iii) E° value for the Mn3+/Mn2+ couple is highly positive (+1.57 V) as compare to Cr3+/Cr2+.


B. Write one similarity and one difference between the chemistry of lanthanoid and actinoid elements.


OR


A. (i) How is the variability in oxidation states of transition metals different from that of the p-block elements?


(ii) Out of Cu+ and Cu2+, which ion is unstable in aqueous solution and why?


(iii) Orange colour of Cr2O72– ion changes to yellow when treated with an alkali. Why?


B. Chemistry of actinoids is complicated as compared to lanthanoids. Give two reasons.

 25

A. An element has atomic mass 93g 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.

B. Write any two differences between amorphous solids and crystalline solids.


OR


A. 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)


B. Give reasons :


(i) In stoichiometric defects, NaCl exhibit Schottky defect and not Frenkel defect.


(ii) Silicon on doping with Phosphorus forms an n-type semiconductor.


(iii) Ferrimagnetic substances show better magnetism than antiferromagnetic substances.