A person is to count 4500 currency notes. Let an denote the number of notes he counts in the nth minute.If a1 =a2 =...=a10 =150 and a10, a11,....arein an A.P. with common difference –2, then the time taken by him to count all notes is

Anonymous User Maths Sequences and Series 30 Mar, 2020 1 Answer 60 views



There are two urns. Urn A has 3 distinct red balls and urn B has 9 distinct blue balls. From each urn two balls are taken out at random and then transferred to the other. The number of ways in which this can be done is

Anonymous User Maths Permutation & Combination 30 Mar, 2020 1 Answer 56 views







From 6 different novels and3 different dictionaries, 4 novels and 1 dictionary are to be selected and arranged in a row on a shelf so that the dictionary is always in the middle. Then the number of such arrangements is

Anonymous User Maths Permutation & Combination 30 Mar, 2020 1 Answer 57 views








A person standing on the bank of a river observes that the angle of elevation of the top of a tree on the opposite bank of the river is 60o and when he retires 40 meters away from the tree the angle of elevation becomes 30o. The breadth of the river is

Anonymous User Maths Trigonometry 30 Mar, 2020 1 Answer 55 views





Solubility product of silver bromide is 5.0 × 10–13. The quantity of potassium bromide (molar mass taken as 120 g mol–1) to be added to 1 litre of 0.05 M solution of silver nitrate to start the precipitation of AgBr is

Anonymous User Chemistry Equilibrium 29 Mar, 2020 1 Answer 69 views


A coin is placed on a horizontal platform which undergoes vertical simple harmonic motion of angular frequency w. The amplitude of oscillation is gradually increased. The coin will leave contact with the platform for the first time

Anonymous User Physics Oscillation 29 Mar, 2020 1 Answer 65 views



The bob of a simple pendulum is a spherical hollow ball filled with water. A plugged hole near the bottom of the oscillating bob gets suddenly unplugged. During the observation, till water is coming out, the time period of oscillation would

Anonymous User Physics Oscillation 29 Mar, 2020 1 Answer 57 views



29.5 mg of an organic compound containing nitrogen was digested according to Kjeldahl's method and the evolved ammonia was absorbed in 20 mL of 0.1 M HCl solution. The excess of the acid required 15 mL of 0.1 M NaOH solution for complete neutralisation. The percentage of nitrogen in the compound is?

Anonymous User Chemistry 29 Mar, 2020 1 Answer 59 views




A particle of mass m is attached to a spring (of spring constant k) and has a natural angular frequency  An external force F(t) proportional tois applied to the oscillator. The time displacement of the oscillator will be proportional to

Anonymous User Physics Oscillation 29 Mar, 2020 1 Answer 53 views



The bob of a simple pendulum executes simple harmonic motion in water with a period t, while the period of oscillation of the bob is tin air. Neglecting frictional force of water and given that the density of the bob is (4/3) × 1000 kg/m3. What relationship between t and t0 is true?

Anonymous User Physics Oscillation 29 Mar, 2020 1 Answer 68 views



Two particles A and B of equal masses are suspended from two massless springs of spring constants k1 and k2, respectively. If the maximum velocities, during oscillations, are equal, the ratio of amplitudes of A and B is

Anonymous User Physics Oscillation 29 Mar, 2020 1 Answer 63 views