A first order reaction takes 10 minutes for 25% decomposition. Calculate t_1/2 for the reaction.

Vapour pressure of water at 20°C is 17.5 mm Hg. Calculate the vapour pressure of water at 20°C when 15g of glucose (molar mass= 180g/mol) is dissolved in 150g of water.

Define the following terms:

(i) Crystalline solids

(ii) Frenkel defect

(iii) n-type semiconductor

Mr. Roy the principle of one reputed school organized a seminar in which he invited parents and principals to discuss the serious issue of diabetes and depression in students. They resolved this issue by strictly banning junk foods in schools and introducing healthy snacks and drinks like soup, lassi, milk etc. in the school canteens. They also made compulsory half an hour of daily physical activities for the students in the morning assembly. After six months, Mr. Roy conducted a health survey in most of the schools and discovered a tremendous improvement in the health of the students.

After reading the above passage, answer the following questions

(i) What are the values (at least 2) displayed by Mr. Roy?

(ii) As a student, how can you spread awareness about this issue?

(iii) What are tranquilizers? Give an example.

(iv) Why is the use of aspartame limited to cold foods and drinks?

(a) Account for the following:

(i) Eu²⁺ is a strong reducing agent

(ii) Transition metals are coloured compounds

(iii) Zn has lowest enthalpy of atomization is the 3d series

(b) Complete the following equations:

(i) KMnO₄

(ii) Cr₂O₇^2- + 14H⁺ + 6Fe²⁺

OR

(a) Account for the following

(i) Transition elements form interstitial compounds.

(ii) Mn³⁺ (3d⁴) is strongly oxidising whereas Cr²⁺ (3d⁴) is strongly reducing.

(iii) Transition metals have high melting point.

(b) What is ‘Misch metal’? Write one use.