Q23 of 40 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, Rupali a Class XII student decided to make others aware about the adverse effects of these carcinogens in foods. She consulted the school principal and requested him to instruct the canteen contractor to stop selling sandwiches, pizzas, burgers and other bakery products to the students. The principal took an immediate action and instructed the canteen contractor to replace the bakery products with some protein and vitamin rich food like fruits, salads, sprouts, etc. The decision was welcomed by the parents and the students.

After reading the above passage, answer the following questions :


(a) What are the values (at least two) displayed by Rupali?


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


(c) Write the two types of secondary structures of proteins.


(d) Give two examples of water soluble vitamins.

(a) Rupali is concerned towards the health of other students and she is caring too.


(b) Starch is polysaccharide component of carbohydrates which is


commonly present in bread.


Note: Polysaccharides are formed when a large number (hundreds to


even thousands) of monosaccharide molecules join together


with the elimination of water molecules.


Starch is the chief food reserve material or storage polysaccharide of plants and is mainly found in seeds, roots, tubers, etc. Wheat, maize, rice, potatoes, barley,bananas are the main source of starch. Starch ocuurs in the form of granules.


(c) The two types of secondary structures of proteins are given below:


(i) α-Helix structure


(ii) β-pleated sheet structure or simple β-structure


(d) The two examples of water soluble vitamins are given below:


(i) Vitamin B1 (Thiamine)


(ii) Vitamin C (Ascorbic acid)


More from this chapter

All 40 →
21

Give reasons for the following :

(a) Red phosphorus is less reactive than white phosphorus.


(b) Electron gain enthalpies of halogens are largely negative.


(c) N2O5 is more acidic than N2O3.

 22

Give reasons for the following :

(a) Acetylation of aniline reduces its activation effect.


(b) CH3NH2 is more basic than C6H5NH2.


(c) Although –MH2 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 show variable oxidation states.


(ii) Zn, cd and Hg are soft metals.


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


(b) Write one similarity and one difference between the chemistry of lanthanoid and actinoid elements.


OR


(a) Following are the transiton metal ions of 3d series :


Ti4+, V2+, Mn3+, Cr3+


(Atomic numbers : Ti = 22, V = 23, Mn = 25, Cr = 24)


Answer the following :


(i) Which ion is most stable in an aqueous solution and why?


(ii) Which ion is a strong oxidizing agent and why?


(iii) Which ion is colourless and why?


(b) Complete the following equations :


(i)


(ii)

25

(a) A 10% solution (by mass) of sucrose in water has a freezing point of 269.15K. Calculate the freezing point of 10% glucose in water if the freezing point of pure water is 273.15 K.

Given :


(Molar mass of sucrose = 342 g mol–1)


(Molar mass of glucose = 180 g mol–1)


(b) Define the following terms :


(i) Molality (m)


(ii) Abnormal molar mass


OR


(a) 30 g of urea (M = 60g mol–1) is dissolved in 846 g of water. Calculate the vapour pressure of water for this solution if vapour pressure of pure water at 298 K is 23.8 mm Hg.


(b) Write two differences between ideal solutions and non-ideal solutions.