An electron in hydrogen atom makes a transition \(n_1 \rightarrow n_2\) where \(n_1\) and \(n_2\) are principal quantum numbers of the two states. Assuming Bohr's model to be valid, the time period of the electron in the initial state is eight times that in the final state. The possible values of \(n_1\) and \(n_2\) are:
| 1. | \( n_1 = 6~\text{and}~n_2 = 2\) | 2. | \( n_1 = 8~\text{and}~ n_2 = 1\) |
| 3. | \( n_1 = 8~\text{and}~ n_2 = 2\) | 4. | \(n_1 = 4~\text{and}~n_2 = 2\) |
Subtopic: Bohr's Model of Atom |
67%
Level 2: 60%+
NEET - 2013
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A person holding a rifle (mass of person and rifle together is \(100\) kg) stands on a smooth surface and fires \(10\) shots horizontally, in \(5\) s. Each bullet has a mass of \(10~\mathrm{g}\) with a muzzle velocity of \(800\) ms-1. The final velocity acquired by the person and the average force exerted on the person are:
1. \(-0.08~ \text{ms}^{-1} ; 16~ \text{N} \)
2. \(-0.8~ \text{ms}^{-1} ; 16~ \text{N} \)
3. \(-1.6~ \text{ms}^{-1} ; 16~ \text{N} \)
4. \(-1.6 ~\text{ms}^{-1} ; 8 ~\text{N}\)
1. \(-0.08~ \text{ms}^{-1} ; 16~ \text{N} \)
2. \(-0.8~ \text{ms}^{-1} ; 16~ \text{N} \)
3. \(-1.6~ \text{ms}^{-1} ; 16~ \text{N} \)
4. \(-1.6 ~\text{ms}^{-1} ; 8 ~\text{N}\)
Subtopic: Newton's Laws |
60%
Level 2: 60%+
NEET - 2013
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A gas in a vessel is initially at pressure \(P.\) If the mass of all the gas molecules is halved and their speed is doubled, then the resultant pressure will be:
| 1. | \(2 P\) | 2. | \(P\) |
| 3. | \(\dfrac{P}{2}\) | 4. | \(4 P\) |
Subtopic: Kinetic Energy of an Ideal Gas |
65%
Level 2: 60%+
NEET - 2013
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A circular coil \(ABCD\) carrying a current \(i\) is placed in a uniform magnetic field. If the magnetic force on the segment \(AB\) is \(\vec{ F},\) then the force on the remaining segment \(BCDA\) is:
1. \(-\vec{F}\)
2. \(3\vec{F}\)
3. \(-3\vec{F}\)
4. \(\vec{F}\)
1. \(-\vec{F}\)
2. \(3\vec{F}\)
3. \(-3\vec{F}\)
4. \(\vec{F}\)
Subtopic: Current Carrying Loop: Force & Torque |
74%
Level 2: 60%+
NEET - 2013
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Two metal rods \((1)\) and \((2)\) of the same length have the same temperature difference between their ends. Their thermal conductivities are \({K}_1\) and \({K}_2\) and cross-sectional areas \({A}_{1}\) and \({A}_{2},\) respectively. If the rate of heat conduction in \((1)\) is four times that in \((2),\) then:
| 1. | \(K_1 A_1=4K_2 {A}_2 \) | 2. | \(K_1 {A}_1=2 {K}_2 {A}_2 \) |
| 3. | \(4 {K}_1{A}_1={K}_2 {A}_2 \) | 4. | \({K}_1 {A}_1={K}_2 {A}_2\) |
Subtopic: Conduction |
74%
Level 2: 60%+
NEET - 2013
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\(\alpha\)- particles, \(\beta\)-particles and \(\gamma\)-rays are all having the same energy. Their penetrating power in a given medium in increasing order will be:
| 1. | \(\gamma , \alpha, \beta \) | 2. | \( \alpha, \beta , \gamma \) |
| 3. | \( \beta, \alpha , \gamma \) | 4. | \(\beta, \gamma, \alpha \) |
Subtopic: Properties of EM Waves |
74%
Level 2: 60%+
NEET - 2013
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A source of light is placed at a distance of \(50\) cm from a photocell and the stopping potential is found to be \(V_0\). If the distance between the light source and photocell is made \(25\) cm, the new stopping potential will be:
| 1. | \(V_0 /2\) | 2. | \(V_0 \) |
| 3. | \(4V_0 \) | 4. | \(2V_0 \) |
Subtopic: Photoelectric Effect: Experiment |
72%
Level 2: 60%+
NEET - 2013
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Vectors \(\vec {\mathrm{A}}, \vec{\mathrm{B}} \) and \(\vec{\mathrm{C}}\) are such that \(\vec{\mathrm{A}} \cdot \vec{\mathrm{B}}=0 \text { and } \vec{\mathrm{A}} \cdot \vec{\mathrm{C}}=0\). Then the vector parallel to \(\vec A\) is:
| 1. | \(\vec{A} \times \vec{B} \) | 2. | \(\vec{B}+\vec{C} \) |
| 3. | \(\vec{B} \times \vec{C} \) | 4. | \(\vec{B}~\text{and} ~\vec{C}\) |
Subtopic: Vector Product |
70%
Level 2: 60%+
NEET - 2013
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One way in which the operation of a \(\text{n-p-n}\) transistor differs from that a \(\text{p-n-p}\):
| 1. | the emitter junction injects minority carriers into the base region of the \(\text{p-n-p}\). |
| 2. | the emitter injects holes into the base of the \(\text{p-n-p}\) and electrons into the base regions of \(\text{n-p}\). |
| 3. | the emitter injects holes into the base of \(\text{n-p-n}\). |
| 4. | the emitter junction is reversed biased in \(\text{n-p}\). |
62%
Level 2: 60%+
NEET - 2013
Hints
Which of the following relations does not give the equation of an adiabatic process, where terms have their usual meaning?
1. \({P}^{1-\gamma}{T}^{\gamma}= \text{constant}\)
2. \({PV}^{\gamma}=\text{constant}\)
3. \({TV}^{\gamma-1}= \text{constant}\)
4. \({P}^{\gamma} {T}^{1-\gamma}=\text{constant}\)
1. \({P}^{1-\gamma}{T}^{\gamma}= \text{constant}\)
2. \({PV}^{\gamma}=\text{constant}\)
3. \({TV}^{\gamma-1}= \text{constant}\)
4. \({P}^{\gamma} {T}^{1-\gamma}=\text{constant}\)
Subtopic: Types of Processes |
74%
Level 2: 60%+
NEET - 2013
Hints
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