6. 7. (a) HO 8. s-block element which cannot be qualitatively confirmed by the flame test is (a) Li (b) Na (c) Rb The oxide which contains an odd electron at the nitrogen atom is (b) NO (c) N2O3 Which one of the following is an example of disproportionation reaction? (d) Be (d) N2O5 (a) 3MnO +4H 2MnO+MnO2 + 2HO (b) MnO +4H+4e MnO2 +2HO (d) 8MnO +30 +HO8MnO2 +6S02+20H 9. (c) 10+2MnO +16H 2Mn +8HO+512 The most common oxidation state of Lanthanoid elements is +3. Which of the following is likely to deviate easily from +3 oxidation state? (a) Ce (At. No. 58) (b) La (At. No. 57) (c) Lu (At. No. 71) (d) Gd (At. No. 64) 10. The measured BOD values for four different water sample (A-D) are as follows A = 3 ppm; B = 18 ppm: C = 21 ppm; D = 4 ppm. (d) B and D The water samples which can be called as highly polluted with organic wastes, are (b) A and D (a) A and B (c) B and C