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प्रश्न
Select the most appropriate option.
Which of the following reactions is exothermic?
पर्याय
H2(g) → 2H(g)
C(s) → C(g)
2Cl(g) → Cl2(g)
H2O(s) → H2O(l)
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उत्तर
2Cl(g) → Cl2(g)
Hint:
Bond is formed between two Cl atoms and hence, energy is released.
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\[\begin{array}{cc}
\phantom{}\ce{H}\phantom{...}\ce{H}\phantom{...................}\ce{H}\phantom{...}\ce{H}\phantom{....}\\
\phantom{.}|\phantom{....}|\phantom{....................}|\phantom{....}|\phantom{.....}\\
\ce{C = C + H - H -> H - C - C - H}\\
\phantom{.}|\phantom{....}|\phantom{....................}|\phantom{....}|\phantom{.....}\\
\phantom{}\ce{H}\phantom{...}\ce{H}\phantom{...................}\ce{H}\phantom{...}\ce{H}\phantom{....}
\end{array}\]
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