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JEE Main Chemistry Model Questions and Answers

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.

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