WBJEE 2025 Question Paper: Download WBJEE Question Paper with Answer Key PDF

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• 1.

  Which one among the following compounds will most readily be dehydrated under acidic condition? 

  

  • Option a
    
  • Option b
    
  • Option c
    
  • Option d
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• 2.

  Manufacturers supply a zener diode with zener voltage \( V_z=5.6\,\text{V} \) and maximum power dissipation \( P_{\max}=\frac14\,\text{W} \). This zener diode is used in the circuit shown. Calculate the minimum value of the resistance \( R_s \) so that the zener diode will not burn when the input voltage is \( V_{in}=10\,\text{V} \). 
  

  • \( 98.56\,\Omega \)
    
  • \( 170.52\,\Omega \)
    
  • \( 306.21\,\Omega \)
    
  • \( 412.37\,\Omega \)
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• 3.

  Two charges \( +q \) and \( -q \) are placed at points \( A \) and \( B \) respectively which are at a distance \( 2L \) apart. \( C \) is the midpoint of \( AB \). The work done in moving a charge \( +Q \) along the semicircle CSD (\( W_1 \)) and along the line CBD (\( W_2 \)) are 
  

  • \( -\frac{qQ}{6\pi\varepsilon_0 L},\; \frac{qQ}{6\pi\varepsilon_0 L} \)
    
  • \( \frac{qQ}{4\pi\varepsilon_0 L},\; -\frac{qQ}{4\pi\varepsilon_0 L} \)
    
  • \( -\frac{qQ}{6\pi\varepsilon_0 L},\; -\frac{qQ}{12\pi\varepsilon_0 L} \)
    
  • \( \frac{qQ}{4\pi\varepsilon_0 L},\; 0 \)
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• 4.

  A piece of granite floats at the interface of mercury and water. If the densities of granite, water and mercury are \( \rho, \rho_1, \rho_2 \) respectively, the ratio of volume of granite in water to that in mercury is 
  

  • \( \frac{\rho_2 - \rho}{\rho - \rho_1} \)
    
  • \( \frac{\rho_2 + \rho}{\rho_1 + \rho} \)
    
  • \( \frac{\rho_1\rho_2}{\rho} \)
    
  • \( \frac{\rho_1}{\rho_2} \)
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• 5.

  One end of a steel wire is fixed to the ceiling of an elevator moving up with an acceleration \( 2\,\text{m/s}^2 \) and a load of \( 10\,\text{kg} \) hangs from the other end. If the cross-section of the wire is \( 2\,\text{cm}^2 \), then the longitudinal strain in the wire is given. (Take \( g=10\,\text{m/s}^2 \) and \( Y=2.0\times10^{11}\,\text{N/m}^2 \)). 
  

  • \( 4\times10^{-6} \)
    
  • \( 3\times10^{-6} \)
    
  • \( 8\times10^{-6} \)
    
  • \( 2\times10^{-6} \)
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