The d- and f-Block Elements — Chemistry STD 12 Science — Question

1. Define the following terms:

1. Mole fraction.
2. Ideal solution.

2. 15.0 g of an unknown molecular material is dissolved in 450 g of water. The resulting solution freezes at - 0.34°C. What is the molar mass of the material?

(K_f for water = 1.86 K kg mol^–1).

1. Give three points of difference between lanthanoids and actinoids.
2. Give reason and select one atom/ion which will exhibit asked property:

1. Sc³⁺ or Cr³⁺ (Exhibit diamagnetic behaviour).
2. Cr or Cu (High melting and boiling point).

write the classification of amino acids and give examples of each.

Describe the physical properties of amines.

The activation energy of a reaction is 75.2kJ mol^-1 in the absence of a catalyst and it lowers to 50.14kJ mol^-1with a catalyst. How many times will the rate of reaction grow in the presence of a catalyst if the reaction proceeds at 25°C?

Answer the following questions:
How will you bring about the following conversions?

1. Ethanamine into methanamine.
2. Aniline into 1, 3, 5-tribromobenzene.
3. Aniline into 4-bromoaniline.

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, Veena, 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 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:

1. What are the values (at least two) displayed by Veena?
2. Which polysaccharide component of carbohydrates is commonly present in bread?
3. Write the two types of secondary structures of proteins.
4. Give two examples of water soluble vitamins.

Explain the oxidation of primary, secondary and tertiary alcohols.

Answer the following questions:
Draw the structures of chromate and dichromate ions.

Describe different electrophilic substitution reaction of chlorobenzene.