Chemistry Class 9th

61. Rutherford used foil in his experiment

A. Aluminum

B. Silver

C. Gold

62. He bombard gold foil with particles

A. Alpha

B. Beta

C. Both a and b

63. The radioactive source used in experiment was

A. Randium

B. Polonium

C. Xenon

64. Alpha particles are charged

A. Positively

B. Negatively

C. Neutral

65. Positively charged central part of atom is called

A. Electron

B. Nucleus

C. Protons

66. Nucleus is responsible for of atom

A. Mass

B. Energy

C. Both a and b

67. This modal based on laws of

A. Motion

B. Gravitation

C. Both a and b

68. Bohr presented atomic theory in ______

A. 1910

B. 1912

C. 1913

69. Electrons revolve around nucleus in circular paths , called

A. Orbit

B. Shell

C. Both a and b

70. The energy of electron in an orbit is depend on

A. Distance of electron from nucleus

B. Type of nucleus

C. No. of electrons

71. Energy of an orbit is ______

A. Fixed

B. Not fixed

C. Vary

72. The energy will be_______ when electron goes from higher energy level to lower

A. Release

B. Absorb

C. No change

73. The energy will be ______ when electron goes from lower energy level to higher

A. Release

B. Absorb

C. No change

74. The energy difference between two levels is given by

A. hf

B. hv

C. Both a and b

75. In E= hv the h is called

A. Plank’s constant

B. Bohr’s constant

C. Both a and b

76. The value of h=

A. 6.02 10^23 s

B. 6.22 10^3 8Js

C. 6.324 10^34Js

77. In formula E= hf the f represents

A. Frequency

B. Time

C. Momentum

78. Angular momentum of an electron is integral multiple of

A. mvr

B. h/2 pi

C. hf

79. Mass of electron in amu is

A. 0.000548597

B. 0.004432

C. 0.046

80. The mass of electron in kg is

A. 9.1 *10^-31kg

B. 9.1* 10^-24kg

C. 9.1 *10^-27kg