Questions for 21-10-2007

1. A student performs an experiment to determine the Young’s modulus of a wire, exactly 2m long, by Searle’s method. In a particular reading, the student measures the extension in the length of the wire to be 0.8 mm with an uncertainty of ± 0.05 mm at a load of exactly 1.0 kg. The student also measures the diameter of the wire to be 0.4 mm with an uncertainty of ± 0.01 mm. Take g = 9.8 m/s^2 (exact). The Young’s modulus obtained from the reading is

(A) (2.0 ± 0.3)*10^11 N/m^2
(B) (2.0 ± 0.2)*10^11 N/m^2
(C) (2.0 ± 0.1)*10^11 N/m^2
(D) (2.0 ± 0.05)*10^11 N/m^2






2.Consider a titration of potassium dichromate solution with acidified Mohr’s salt solution using diphenylamine as indicator.

The number of moles of Mohr’s salt required per mole of dichromate is
(A) 3 (B) 4 (C) 5 (D) 6



IIT.JEE 2007 SOLUTIONS.MATHEMATICS
3. The letters of the word COCHIN are permuted and all the permutations are arranged in an alphabetical order as in an English dictionary. The number of words that appear before the word COCHIN is


(A) 360 (B) 192 (C) 96 (D) 48