ધોરણ 8 વિજ્ઞાન સ્વ અધ્યયન પોથી ,dhoran 8 ch 12 vigyan swadhyay pothi , std 8 vigyan svadhyaypothi

2. Real and distinct 3. 1 2 4. No 6. Al real values 5. 11. f(r 2, whert is any real number 14. 64 Mcas 1. Tr the equation a U has real and distinct Toots, then 2. If rive equation 1 has twu distinct routs, then fb) Isil 2 try lal 2 (d) Norve of Lhese 3. the equation y 2-6 i o has equal Tools, then thr roots arr ha 4) If i br r. 0 has qual roots, then -I 5)If the equation arz 2r a has two distinct roots, if r (a) a ti b) 0 (ch w 0,1 (d) --1. e positive value of for which the e sr will both have real roots, is b) 8 (c) 12 (d) 16

CH. 14 STATISTICS Q1 Class 0-8 8-16 16-24 24-32 32-40 Frequency 10 12 26 9 15 e mean of above data by: () Direct method () Assumed mean method (ii) Step deviati iop metod. Q2 The following distribution shows the daily pocket allowance of children of a locali ty. The mean pocket allowance is Rs 20. Find the missing frequency Daily Pocket 0-20 20-40 40-60 0-80 80-100 No. Of Children 7 10 9 13 Q3. The following table shows age distribution of persons in a particular region. Find the: (0) mean age (i)modal age (ili) median age Age? Below!0 Below20 Below30 Below 40, Below 50 Belo No, persons ? 250 190 100 40 15 4 Arithmetic mean of the following frequency distribution is 50. Find the missing frequencies C.I. ? 0-20 20-40 40-60 60-80 80-100 Tota

The C-H bond of the side chain in toluene, C_(6)H_(5)-CH_(3) , has a dissociation energy of 77.5 kcal mol^(-1) . Calculate Delta_(f)H^(Theta) of benzy 1 radical and the strength of the central bond in dibenzy 1 C_(6)H_(5)-CH_(2)-CH_(2)-C_(6)H_(5) given that Delta_(f)H^(Theta) to toluene vapour in 12 kcal mol^(-1) and that of dibenzy 1 vapour is 27.8 kcal mol^(-1). BE of H_(2) = 104 kcal mol^(-1) .