Practice Questions

Q37.The heat of atomization of methane and ethane are 360 kJ mol−1 and 620 kJ mol−1 , respectively. The longest wavelength of light capable of breaking the C −C bond is (Avogadro's number = 6.023 × 1023, h = 6.62 × 10−34 J s) (1) 2.48 × 104 nm (2) 1.49 × 104 nm (3) 2.48 × 103 nm (4) 1.49 × 103 nm

Q61.The largest value of r, for which the region represented by the set {ω ∈C||ω −4 −i| ≤r} is contained in the region represented by the set {z ∈C||z −1| ≤|z + i|}, is equal to : (1) 2√2 (2) 32 √2 (3) √17 (4) 52 √2

Q24.The focal lengths of objective lens and eye lens of a Galilean Telescope are respectively 30 cm and 3.0 cm. Telescope produces virtual, erect image of an object situated far away from it at least distance of distinct vision from the eye lens. In this condition the Magnifying Power of the Galilean Telescope should be : (1) +8. 8 (2) −11. 2 (3) +11. 2 (4) −8. 8 JEE Main 2014 (09 Apr Online) JEE Main Previous Year Paper

Q23.A thin glass plate of thickness is 2500 λ ( λ is wavelength of light used) and refractive index μ = 1.5 is inserted 3 between one of the slits and the screen in Young's double slit experiment. At a point on the screen equidistant from the slits, the ratio of the intensities before and after the introduction of the glass plate is : (1) 2 : 1 (2) 1 : 4 (3) 4 : 1 (4) 4 : 3

Q27.A copper ball of radius 1 cm and work function 4.47 eV is irradiated with ultraviolet radiation of wavelength 2500 Å . The effect of irradiation results in the emission of electrons from the ball. Further the ball will acquire charge and due to this there will be a finite value of the potential on the ball. The charge acquired by the ball is : (1) 5.5 × 10−13 C (2) 7.5 × 10−13 C (3) 4.5 × 10−12 C (4) 2.5 × 10−11 C

Q51.The magnetic moment of the complex anion [Cr(NO) (NH3)(CN)4]2− is : (1) 5.91BM (2) 3.87BM (3) 1.73BM (4) 2.82BM

Q75. a a + 1 a −1 a + 1 b + 1 c −1 Let a, b, c be such that b(a + c) ≠0. If −b b + 1 b −1 + a −1 b −1 c + 1 = 0, then the c c −1 c + 1 (−1)n+2a (−1)n+1b (−1)nc value of ' n ' is (1) zero (2) any even integer (3) any odd integer (4) any integer JEE Main 2009 JEE Main Previous Year Paper