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NEET Sample Paper NEET Sample Test Paper-54

  • question_answer
    \[{{H}_{2}}(g)+\frac{1}{2}{{O}_{2}}(g)\,\,\to \,\,{{H}_{2}}O\,(\ell )\] \[B.E\left( H-H \right)={{x}_{1}},\,\,B.E\left( O=O \right)={{x}_{2}};\,\,B.E\left( O-H \right)={{x}_{3}}\]Latent heat of vaporisation of water liquid into water vapour \[\text{=}\,\,{{x}_{4}}\text{ }then\text{ }\Delta {{H}_{f}}\] (that of formation of water) is-

    A) \[{{x}_{1}}+\frac{{{x}_{2}}}{2}-{{x}_{3}}+{{x}_{4}}\]

    B) \[2{{x}_{3}}-{{x}_{1}}-\frac{{{x}_{2}}}{2}-{{x}_{4}}\]

    C) \[{{x}_{1}}+\frac{{{x}_{2}}}{2}-2{{x}_{3}}-{{x}_{4}}\]

    D) \[{{x}_{1}}+\frac{{{x}_{2}}}{2}-2{{x}_{3}}+{{x}_{4}}\]

    Correct Answer: C

    Solution :

    \[{{H}_{2}}\,\,+\,\,\frac{1}{2}{{O}_{2}}\,\to \,\,{{H}_{2}}O\,\,\,\,\,\,\,\Delta H\,\,=\,\,?\] \[\Delta H\,\,=\,\,{{\left( B.E. \right)}_{R}}\,\,-\,\,{{\left( B.E. \right)}_{p}}\] \[\Delta H=\left[ {{x}_{1}}+\frac{1}{2}\,\,\times \,\,{{x}_{2}} \right]\,\,-\,\,\left[ 2{{x}_{3}} \right]\text{ }\,\,i.e.\text{ }for\text{ }{{H}_{2}}O\,(\ell )\] Adding \[\underset{(\ell )}{\mathop{{{H}_{2}}O}}\,\,\,\to \,\,\text{ }\underset{(g)}{\mathop{{{H}_{2}}O}}\,\,\text{ }\Delta H={{x}_{4}}\]


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