MCQ
An exothermic reaction is one which
- ATakes place only on heating
- BIs accompanied by a flame
- CIs accompanied by a absorption of heat
- ✓Is accompanied by evolution of heat
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The heat of the reaction $2Mg + Si{O_2} \to 2MgO + Si$ is......$kJ$
| column $I$ | column $II$ |
| $(A)$ $CO _2( s ) \rightarrow CO _2( g )$ | $(p)$ phase transition |
| $(B)$ $CaCO _3( s ) \rightarrow CaO$ (s) $+ CO _2( g )$ | $(q)$ allotropic change |
| $(C)$ $2 H \bullet \rightarrow H _2( g )$ | $(r)$ $\Delta H$ is positive |
| $(D)$ $P_{\text {(white, solid) }} \rightarrow P_{\text {(red, solid) }}$ | $(s)$ $\Delta S$ is positive |
| $(t)$ $\Delta S$ is negative |