IIT JEE Main Model Questions – Page 5

1. A particle is projected from point A with velocity u at an angle α with horizontal. In its parabolic path, at point P the particle is moving at right angles to its initial direction of projection. Its velocity at P is
A) u tan α B) u cot α
C) u cos α D) u cosec α

2. The angular speed of the second’s hand of a clock is
A) (1/60) rad/s B) (π/60) rad/s
C) (2π/60) rad/s D) (360/60) rad/s

3. In a thermo dynamical process pressure of fixed mass of gas is changed in such a way that the gas molecules give out 30 J of heat and 10 J of work is done on the gas. If the internal energy of the gas was 40 J, the final internal energy will be
A) zero B) 80 J C) 20 J D) – 20 J

4. A body travelling along a straight line traversed one third of the total distance with a velocity 4 m/s. The remaining part of the distance was covered with a velocity 2 m/s for half the time and with velocity 6 m/s for
the other half of time. The mean velocity averaged over the whole time of motion is
A) 5 m/s B) 4 m/s C) 4.5 m/s D) 3.5m/s

5. A body is placed on a rough inclined plane of inclination θ. As the angle θ is increased from 0o to 90o the contact force between the block and the plane
A) remains constant
B) first remains constant then decreases
C) first decreases then increases
D) first increases then decreases

Key: 1)B 2)C 3)C 4)B 5)B

1. The dissociation energy of H2 is 430.53 kJ mol-1. If hydrogen is dissociated by illumination with radiation of wavelength 253.7nm, the fraction of the radiant energy which will be converted into kinetic energy is given by
A) 1.22% B) 8.76% C) 2.22% D) 100%

2. The number of concentric spherical surfaces for 3s orbital at which the probability of finding the electron is zero, are
A) 0 B) 1 C) 2 D) 3

3. Select correct statement
A) Oxides and peroxides of alkali metals are diamagnetic and colourless
B) Superoxides are paramagnetic
C) Li and Na do not form superoxides
D) All are correct statements

4. Be and Al resemble in the following but not in
A) both form electron deficient hydrides
B) both are rendered passive by HNO3
C) both form amphoteric oxides
D) both have sp-hybridisation in their compounds

5. In an atom two electrons move around the nucleus in circular orbits of radii R and 4R.
The ratio of the time taken by them to completeone revolution is
A) 1 : 4 B) 4 : 1 C) 1 : 8 D) 8 : 7

6. 190.0 ml of N2 was collected in a jar over water at some temperature, water level inside and outside the jar standing at the same height. If barometer reads 740 mm Hg and aqueous tension at the temperature of the experiment is 20 mm Hg, the volume of the gas at 1 atm pressure and at the same temperature would be
A) 185.0 ml B) 180.0 ml C) 195.0 ml D) 200 ml

7. An energy of 24.6eV is required to remove one of the electrons from a helium atom. The energy required to remove both the electrons from helium atom is
A) 38.2eV B) 49.2eV C) 51.8eV D) 79.0eV

8. The total number of orbitals in the principal shell of He+ that has energy equal to hcR/4, is (R = Rydberg constant)
A) 4 B) 16 C) 9 D) none of these

9. To neutralize completely 20mL of 0.1 M aqueous solution of phosphorous acid, the volume of 0.1 M aqueous KOH solution required is
A) 60mL B) 20mL C) 40mL D) 10mL

KEY: 1)B 2)C 3)D 4)D 5)C 6)B 7)D 8)B 9)C.

JEE Main Physics Practice Questions with Answers

JEE Main Chemistry Model Questions and Answers