Q&A - Ask Doubts and Get Answers

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Medical
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In acidic medium, H_{2}O_{2} changes Cr_{2}O_{7}^{-2} to CrO_{5} which has two (-O-O) bonds. Oxidation state of Cr in CrO_{5} is:-

  • Option 1)

    +5

  • Option 2)

    +3

  • Option 3)

    +6

  • Option 4)

    -10

 
  Exceptional configuration in '3d' series - Due to half fill stable configuration is stable in configuration at the place of . Similarly, stable with at the place of . -    The reaction proceeds as follows: In peroscide linkages, the ascidation state of each axygen atom is -1. Let O.S. of be x Then, x-2-2*2=0 = x=+6 O.S, is +6 Option 1) +5 This is incorrect option Option 2) +3 This is...
Medical
100 Views   |  

Which of the following complexes is used as an anti-cancer agent:

  • Option 1)

    mer-\left [ Co(NH_{3})_{3}Cl_{3} \right ]

  • Option 2)

    cis-\left [ PtCl_{2}(NH_{3})_{2} \right ]

  • Option 3)

    cis-K_{2}\left [ PtCl_{2}Br_{2} \right ]

  • Option 4)

    Na_{2}CoCl_{4}

 
As we learned in concept Geometrical Isomers - This is due to the difference in relative position of the ligands attached to the central metal atom with respect to each other -    Cis and is used as an anti cancer agent.   Option 1) This option is incorrect. Option 2) This option is correct. Option 3) This option is incorrect. Option 4) This option is incorrect.
Medical
111 Views   |  

Among the following complexes the one which shows zero crystal field stabilization energy (CFSE):

  • Option 1)

    \left [ Mn(H_{2}O)_{6} \right ]^{3+}

  • Option 2)

    \left [ Fe(H_{2}O)_{6} \right ]^{3+}

  • Option 3)

    \left [ Co(H_{2}O)_{6} \right ]^{2+}

  • Option 4)

    \left [ Co(H_{2}O) _{6}\right ]^{3+}

 
As we learnt in  CFSE in octahedral complex - -    for Fe3+  we have     Option 1) Incorrect Option 2) Correct Option 3) Incorrect Option 4) Incorrect
Medical
228 Views   |  

The force 'F' acting on a particle fo mass 'm' is indicated by the force-time graph shown below. The change in momentum of the particle over the time interval from zero to 8 s is:

  • Option 1)

    24 Ns

  • Option 2)

    20Ns

  • Option 3)

    12Ns

  • Option 4)

    6Ns

 
As we discussed in concept Impulse - - wherein    Change in momentum Area of - area of rectange + area of rectange   Option 1) 24 Ns This option is incorrect. Option 2) 20Ns This option is incorrect. Option 3) 12Ns This option is correct. Option 4) 6Ns This option is incorrect.
Medical
565 Views   |  

A balloon with mass 'm' is descending down with an acceleration 'a' (where a<g). How much mass should be removed from it so that it starts moving up with an acceleration 'a'?

  • Option 1)

    \frac{2ma}{g+a}

  • Option 2)

    \frac{2ma}{g-a}

  • Option 3)

    \frac{ma}{g+a}

  • Option 4)

    \frac{ma}{g-a}

 
As we learnt in  Newton's 2nd Law -     Therefore   - wherein  in C.G.S & S.I  When ballon descending down = upthrust force When ballon moving up from equations (i) and (ii) we get   Option 1) This option is correct. Option 2) This option is incorrect. Option 3) This option is incorrect. Option 4) This option is incorrect.
Medical
402 Views   |  

Dependence of intensity of gravitational field (E) of earth with distance (r) from centre of earth is correctly represented by

  • Option 1)

  • Option 2)

  • Option 3)

  • Option 4)

 
As we learnt in Gravitational field intensity due to Uniform solid sphere - Outside surface  * on the surface - wherein * Inside surface         Intensity due to spherical shell -  Radius of shell  Position of Pt.  Mass of spherical shell - wherein Outside the surface  on the surface inside the surface      For the point inside the earth ( r < R) At centre r = 0                E =...
Medical
88 Views   |  

A black hole is an object whose gravitational field is so strong that even light cannot escape from it. To what approximately radius would earth (mass=5.98X10^{24} kg) have to be compressed to be a black hole?

  • Option 1)

    10^{-9}m

  • Option 2)

    10^{-6} m

  • Option 3)

    10^{-2} m

  • Option 4)

    100m

 
As we learnt in Escape velocity ( in terms of radius of planet) -  Escape velocity Radius of earth - wherein depends on the reference body greater the value of  or  greater will be the escape velocity   For earth     Option 1) Incorrect Option Option 2) Incorrect Option Option 3) Correct Option Option 4) 100m Incorrect Option
Medical
409 Views   |  

Two thin dielectric slabs of dielectric constants K1 and K2 (K1 < K2) are inserted between plates of a parallel plate capacitor, as shown in the figure. The variation of electric field "E" between the plates with distance "

  • Option 1)

  • Option 2)

  • Option 3)

  • Option 4)

 
As we learnt in  Dielectric Constant (K) -   - wherein K is also known as relative permittivity .    Electric field in dielectric decreases and outside it is higher.comparing dielectric 1 and 2 electric fields is smaller in a dielectric   Option 1) Incorrect Option 2) Incorrect Option 3) Incorrect Option 4) Correct
Medical
307 Views   |  

In a region, the potential is represented by V(x,y,z) = 6x - 8xy - 8y + 6yz, where V is in volts and x, y, x are in metres. The electric force experienced by a charge of 2 coulomb situated at point (1, 1, 1) is:

  • Option 1)

    6\sqrt{5} N

  • Option 2)

    30 N

  • Option 3)

    24 N

  • Option 4)

    4\sqrt 35 N

 
  In space -   ,      ,   -       Option 1) N Incorrect Option 2) 30 N Incorrect Option 3) 24 N Incorrect Option 4) 4 N Correct
Medical
155 Views   |  

A conducting sphere of radius R is given a charge Q. The electric potential and the electric field at the centre of the sphere respectively are:

  • Option 1)

    zero and \frac{Q}{4 \pi \varepsilon R^{2}}

  • Option 2)

    \frac{Q}{4 \pi \varepsilon_{0} R} and Zero

  • Option 3)

    \frac{Q}{4 \pi \varepsilon_{0} R} and \frac{Q}{4 \pi \varepsilon_{0} R^{2}}

  • Option 4)

    Both are zero

 
  Inside the sphere (P lies inside the sphere) - - wherein   The electric field inside conducting sphere  potential inside conducting sphere    Option 1) zero and  Incorrect Option 2)  and Zero Correct Option 3)  and  Incorrect Option 4) Both are zero Incorrect
Medical
122 Views   |  

The given graph represents V - I Characteristic for a semiconductor device.

Which of the following statement is correct? 

  • Option 1)

    It is V - I Characteristic for solar cell where, point A represents open circuit voltage and point B Short circuit current.

  • Option 2)

    It is a for a solor cell and point And B represent open circuit viltage and current respectively.

  • Option 3)

    It is a for a photodiode and poins A and B represent open circuit voltage and current respectively.

  • Option 4)

    It is a for a LED points And B represent open circuit voltage and short circuit current respectively.

 
  Solar cells - It is based on photovoltic effect .It  convert solar energy into electrical energy . - wherein One of the semi conductor region is made so thin that the light incident on it reaches the PN junction and get absorbed .    This represent V-I characteristics for solar cell where point A represents open circuit voltage and point B short circuit voltage.   Option 1) It is V - I...
Medical
95 Views   |  

A transformer having efficiency of 90% is working on 200V and 3kW power supply. If the current in the secondary coil is 6A, the voltage across the secondary coil and the current in the primary coil respectively are:

  • Option 1)

    300V, 15A

  • Option 2)

    450V, 15A

  • Option 3)

    450V, 13.5A

  • Option 4)

    600V, 15A

 
  Efficiency of transformer - % -    power supply=3KW at 90% efficiency power in secondary coil is = 2.7KW Current in primary coil Option 1) 300V, 15A This is incorrect option Option 2) 450V, 15A This is correct option Option 3) 450V, 13.5A This is incorrect option Option 4) 600V, 15A This is incorrect option
Medical
213 Views   |  

A thin semicircular conducting ring (PQR) of radius 'r' is falling with its plane vertical in a horizontal magnetic field B, as shown in figure. The potential difference developed across the ring when its speed is v, is:

  • Option 1)

    zero

  • Option 2)

    \frac{Bv\pi r^{2}}{2}  and  P is at higher potential

  • Option 3)

    \pi rBv and R is at higher potential

  • Option 4)

    2rBv and R is at higher potential

 
  Motional EMF -   - wherein magnetic field length velocity of u perpendicular to uniform magnetic field.    Potential developed depends on displacement between end points i.e. 2R point R will be at higher potential. Option 1) zero This is incorrect option Option 2)   and  P is at higher potential This is incorrect option Option 3) and R is at higher potential This is incorrect...
Medical
107 Views   |  

Light with an energy of 25\times 10^{4} Wm^{-2} falls on a perfectly reflecting surface at normal incidence. If the surface area is 15 cm^{2}, the average force exerted on the surface is:-

  • Option 1)

    1.25\times 10^{-6}N

  • Option 2)

    2.50\times 10^{-6}N

  • Option 3)

    1.20\times 10^{-6}N

  • Option 4)

    3.0\times 10^{-6}N

 
  Momentum of EM wave - - wherein u = Energy of EM wave c = Speed of light in vacuum      For a perfectly reflecting surface  Option 1) This solution is incorrect  Option 2) This solution is correct  Option 3) This solution is incorrect  Option 4) This solution is incorrect 
Medical
116 Views   |  

When the energy of the incident radiation is increased by 20%, the kinetic energy of the photoelectrons emitted from a metal surface increased from 0.5 eV to 0.8 eV. the work functionof the metal is:

  • Option 1)

    0.65 eV

  • Option 2)

    1.0 eV

  • Option 3)

    1.3 eV

  • Option 4)

    1.5 eV

 
As we discussed in concept Conservation of energy -   - wherein    Let work function is Initial energy of incidence = E => Kinetic energy = -----(1) Finally, ------(2) From (1) => => Option 1) 0.65 eV This option is incorrect. Option 2) 1.0 eV This option is correct. Option 3) 1.3 eV This option is incorrect. Option 4) 1.5 eV This option is incorrect.
Medical
128 Views   |  

Two cities are 150km apart. Electric power is sent from one city to another city through copper wires. the fall of potential per km is 8 volt and the average resistance per km is 0.5\Omega. The power loss in the wires is:

  • Option 1)

    19.2W

  • Option 2)

    19.2kW

  • Option 3)

    19.2J

  • Option 4)

    12.2kW

 
  Power dissipiated in external resistance - -    Power loss= Power loss=  Option 1) 19.2W This option is incorrect. Option 2) 19.2kW This option is correct. Option 3) 19.2J This option is incorrect. Option 4) 12.2kW This option is incorrect.
Medical
94 Views   |  

The resistance in the two arms of the meter bridge  are 5\Omega and R\Omega, respectivilty. When the resistance R is shunted with an equal resistance, the new balance point is at 1.6\ l_{1} . The resistance 'R' is:

  • Option 1)

    10\Omega

  • Option 2)

    15\Omega

  • Option 3)

    20\Omega

  • Option 4)

    25\Omega

 
  Meter bridge - To find the resistance of a given wire using a meter bridge and hence determine the specific resistance of its materials - wherein       Divide  and  Or,  From equation  Option 1) 10 This option is incorrect. Option 2) 15 This option is correct. Option 3) 20 This option is incorrect. Option 4) 25 This option is incorrect.