NEET Physics Thermometry, Calorimetry & Thermal Expansion Question Bank Mock Test - Thermal Properties of Matter

  • question_answer
    A piece of metal weight 46 g in air, when it is immersed in the liquid of specific gravity 1.24 at \[27{}^\circ C\]it weighs 30 g. When the temperature of liquid is raised to \[42{}^\circ C\]the metal piece weight 30.5 g, specific gravity of the liquid at \[42{}^\circ C\] is 1.20, then the linear expansion of the metal will be

    A) \[3.316\times {{10}^{-5}}{{/}^{0}}C\]          

    B) \[2.316\times {{10}^{-5}}{{/}^{0}}C\]

    C) \[4.316\times {{10}^{-5}}{{/}^{0}}C\]

    D) None of these

    Correct Answer: B

    Solution :

    [b] Loss of weight at \[27{}^\circ C\]is \[=46-30=16={{V}_{1}}\times 1.24{{\rho }_{l}}\times g...(i)\] Loss of weight at \[42{}^\circ C\]is \[=46-30.5=15.5={{V}_{2}}\times 1.2{{\rho }_{l}}\times g...(ii)\] Now dividing (i) by (ii), we get\[\frac{16}{15.5}=\frac{{{V}_{1}}}{{{V}_{2}}}\times \frac{1.24}{1.2}\] But\[\frac{{{V}_{1}}}{{{V}_{2}}}=1+3\alpha ({{t}_{2}}-{{t}_{1}})=\frac{15.5\times 1.24}{16\times 1.2}=1.001042\] \[\Rightarrow 3\alpha (42{}^\circ -27{}^\circ )=0.001042\Rightarrow \alpha =2.316\times {{10}^{-5}}/{}^\circ C\]


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