MCQOPTIONS
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MCQOPTIONS
This section includes 17 Mcqs, each offering curated multiple-choice questions to sharpen your Physics knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
A hydrogen atom is excited from n = 1 to n = 3. What is the value of energy absorbed by the atom? |
| A. | 9.06 eV |
| B. | 12.09 eV |
| C. | 13.6 eV |
| D. | 10.2 eV |
| Answer» C. 13.6 eV | |
| 2. |
At a given instant, say t = 0, two radioactive substances A and B have equal activities. The ratio \(\frac{{{{\rm{R}}_{\rm{B}}}}}{{{{\rm{R}}_{\rm{A}}}}}\) of their activities after time t itself decays with time t as e-3t. If the half-life of A is ln2, the half-life of B is: |
| A. | 4ln 2 |
| B. | \(\frac{{{\rm{ln\;}}2}}{2}\) |
| C. | \(\frac{{{\rm{ln\;}}2}}{4}\) |
| D. | 2ln 2 |
| Answer» D. 2ln 2 | |
| 3. |
According to classical electromagnetic theory, an accelerating charged particle emits radiation in the form of electromagnetic waves. The energy of an accelerating electron should therefore, ____________. |
| A. | continuously increase |
| B. | continuously decrease |
| C. | take random values |
| D. | be always constant |
| Answer» C. take random values | |
| 4. |
Ionising ______ has/have sufficient energy to affect the atoms in living cell and thereby damage their genetic material. |
| A. | Water |
| B. | Chemicals |
| C. | Radiation |
| D. | Reaction |
| Answer» D. Reaction | |
| 5. |
In a radioactive decay chain, the initial nucleus \(I{}_{90}^{232}\;\) Th. At the end, there are 6 α -particles and 4-β particles which are emitted. If the end nucleus is \({}_Z^AX\), A and Z are given by |
| A. | A = 202, Z = 80 |
| B. | A = 208, Z = 82 |
| C. | A = 200, Z = 81 |
| D. | A = 208, Z = 80 |
| Answer» C. A = 200, Z = 81 | |
| 6. |
In a process, temperature and volume of one mole of an ideal monoatomic gas are varied according to the relation VT = k, where k is a constant. In this process, the temperature of the gas is increased by ∆T. The amount of heat absorbed by gas is (where, R is gas constant) |
| A. | \(\frac{1}{2}kR\Delta T\) |
| B. | \({\rm{\;}}\frac{{2k}}{3}\Delta T\) |
| C. | \(\frac{1}{2}R\Delta T\) |
| D. | \(\frac{3}{2}R\Delta T\) |
| Answer» D. \(\frac{3}{2}R\Delta T\) | |
| 7. |
A hydrogen atom, initially in the ground state is excited by absorbing a photon of wavelength 980 A. The radius of the atom in the excited state in terms of Bohr radius a0 will be (Take hc = 12500 eV-A) |
| A. | 4a0 |
| B. | 9a0 |
| C. | 16a0 |
| D. | 25a0 |
| Answer» D. 25a0 | |
| 8. |
If ‘M’ is the mass of water that rises in a capillary tube of radius 'r', then mass of water which will rise in a capillary tube of radius ‘2r’ is: |
| A. | M |
| B. | \(\frac{M}{2}\) |
| C. | 4M |
| D. | 2M |
| Answer» E. | |
| 9. |
Electrons in atoms and molecules can change energy levels by emitting or absorbing |
| A. | Protons |
| B. | Photons |
| C. | electrons |
| D. | All of these |
| Answer» C. electrons | |
| 10. |
Atom of any element is |
| A. | Positively charged |
| B. | Uncharged |
| C. | Negatively charged |
| D. | Charged positive or negative |
| Answer» C. Negatively charged | |
| 11. |
In Li++, electron in first Bohr orbit is excited to a level by a radiation of wavelength λ. When the ion gets deexcited to the ground state in all possible ways (including intermediate emissions), a total of six spectral lines are observed. What is the value of λ?(Given: h = 6.63 × 10-34 Js; c = 3 × 108 ms-1) |
| A. | 11.4 nm |
| B. | 9.4 nm |
| C. | 12.3 nm |
| D. | 10.8 nm |
| Answer» E. | |
| 12. |
In the nucleus of uranium-235 there are? |
| A. | 235 neutrons |
| B. | 235 protons |
| C. | A total of 235 protons and neutrons |
| D. | 235 electrons |
| Answer» D. 235 electrons | |
| 13. |
A sample of radioactive material A, that has an activity of 10 mCi (1 Ci = 3.7 × 1010 decays/s), has twice the number of nuclei as another sample of a different radioactive material B which has an activity of 20 mCi. The correct choices for half-lives of A and B would then be respectively: |
| A. | 5 days and 10 days |
| B. | 10 days and 40 days |
| C. | 20 days and 5 days |
| D. | 20 days and 10 days |
| Answer» D. 20 days and 10 days | |
| 14. |
Radiation coming from transitions n = 2 to n = 1 of hydrogen atoms fall on He+ ions in n = 1 and n = 2 states. The possible transition of helium ions as they absorb energy from the radiation is: |
| A. | n = 2 → n = 3 |
| B. | n = 1 → n = 4 |
| C. | n = 2 → n = 5 |
| D. | n = 2 → n = 4 |
| Answer» E. | |
| 15. |
In a hydrogen like atom, when an electron jumps from the M-shell to the L-shell, the wavelength of emitted radiation is λ. If an electron jumps from N-shell to the L-shell, the wavelength of emitted radiation will be |
| A. | \(\frac{{27}}{{20}}\lambda \) |
| B. | \(\frac{{25}}{{16}}\lambda\) |
| C. | \(\frac{{20}}{{27}}\lambda\) |
| D. | \(\frac{{16}}{{25}}\lambda\) |
| Answer» D. \(\frac{{16}}{{25}}\lambda\) | |
| 16. |
In a Frank-Hertz experiment, an electron of energy 5.6 eV passes through mercury vapour and emerges with an energy 0.7 eV. The minimum wavelength of photons emitted by mercury atoms is close to |
| A. | 250 nm |
| B. | 2020 nm |
| C. | 1700 nm |
| D. | 220 nm |
| Answer» B. 2020 nm | |
| 17. |
A He+ ion is in its first excited state. Its ionization energy is: |
| A. | 48.36 eV |
| B. | 54.40 eV |
| C. | 13.60 eV |
| D. | 6.04 eV |
| Answer» D. 6.04 eV | |