MCQOPTIONS
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MCQOPTIONS
This section includes 114 Mcqs, each offering curated multiple-choice questions to sharpen your 12th knowledge and support exam preparation. Choose a topic below to get started.
| 101. |
An αα-particle accelerated through V volt is fired towards a nucleus. Its distance of closest approach is r. If a proton accelerated through the same potential is fired towards the same nucleus, the distance of closest approach of proton will be : |
| A. | r |
| B. | 2r |
| C. | r/2 |
| D. | r/4 |
| Answer» B. 2r | |
| 102. |
αα-particles are projected towards the nuclei of the following metals, with the same kinetic energy. Towards, which metal, the distance of closest approach is minimum ? |
| A. | Cu (Z = 29) |
| B. | Ag (Z = 47) |
| C. | Au (Z = 79) |
| D. | Pd (Z = 46) |
| Answer» B. Ag (Z = 47) | |
| 103. |
A proton and an alpha particle having same momentum enter a magnetic field at right angles to it. If r1r1and r2r2 be their radii respectively then value of r1/r2r1r2 is : |
| A. | 1 |
| B. | 2 |
| C. | 1/2 |
| D. | 1/4 |
| Answer» C. 1/2 | |
| 104. |
Minimum excitation potential of Bohr's first orbit in hydrogen atom is: |
| A. | 13.6 V |
| B. | 3.4 V |
| C. | 10,2 V |
| D. | 3.6 V |
| Answer» D. 3.6 V | |
| 105. |
In the lowest orbit, the binding energy of an electron in hydrogen atom is 13.6 eV. The energy required to take out the electron from the lower three orbits in (eV) will be: |
| A. | 13.6, 6.8, 8.4 |
| B. | 13.6, 10.2, 3.4 |
| C. | 13.6, 27.2, 40.8 |
| D. | 13.6, 3.4, 1.5 |
| Answer» E. | |
| 106. |
The velocity of an electron in its fifth orbit, if the velocity of an electron in the second orbit of sodium atom (atomic number = 11) is vv, will be : |
| A. | v |
| B. | 22 5 v |
| C. | 5 2 v |
| D. | 2 5 v |
| Answer» E. | |
| 107. |
The order of size of nucleus and Bohr radius of an atom respectively are: |
| A. | 10 − 14 m , 10 − 10 m |
| B. | 10 − 10 m , 10 − 8 m |
| C. | 10 − 20 m , 10 − 16 m |
| D. | D 10 − 8 m , 10 − 6 m |
| Answer» B. 10 − 10 m , 10 − 8 m | |
| 108. |
For electron moving in nth orbit of the atom, the angular velocity is proportional to : |
| A. | n |
| B. | 1 / n |
| C. | n 3 |
| D. | 1 / n 3 |
| Answer» E. | |
| 109. |
In terms of Rydberg Constant R, the wave number of the first Balmer line is : |
| A. | R |
| B. | 3R |
| C. | 5 R 36 |
| D. | 8 R 9 |
| Answer» C. 5 R 36 | |
| 110. |
If Bohr's radius is R0 then radius of 3rd orbit of hydrigen atom will be: |
| A. | 3R0 |
| B. | 6R0 |
| C. | 9R0 |
| D. | 12R0 |
| Answer» C. 9R0 | |
| 111. |
The radius of hydrogen atom, when it is in its second excited state, becomes : |
| A. | half |
| B. | double |
| C. | four times |
| D. | nine times |
| Answer» B. double | |
| 112. |
Number of electrons that constitute one ampere of current is : |
| A. | 265x1016 |
| B. | 625x1012 |
| C. | 4.8 x 1010 |
| D. | D 625x1016 |
| Answer» C. 4.8 x 1010 | |
| 113. |
The mass and energy equivalent to 1 a.m.u. respectively are : |
| A. | 1.67 x 10-27 g, 9.30 MeV |
| B. | 1.67 x 10-27 kg, 930 MeV |
| C. | 1.67 x 10-27 kg, 1 MeV |
| D. | D 1.67 x 10-34 kg, 1 MeV |
| Answer» C. 1.67 x 10-27 kg, 1 MeV | |
| 114. |
The mass of an electron in motion depends upon: |
| A. | direction of motion |
| B. | its velocity |
| C. | its velocity of e- |
| D. | D its shell number |
| Answer» C. its velocity of e- | |