Answer : 
Explanation : In the molecule of the hydrogen bonding forces tend to resist any phase transition form liquid state to gaseous phase, and these hydrogen bonding forces are greater usually when the hydrogen is bound to an electronegative atom like chlorine, fluorine,oxygen,etc. This then lowers the viscosity of the compound.
Answer is (1) - no reaction.
<em>Explanation;
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Some of you may think this reaction as a single replacement reaction which gives NaBr + F₂ as products.
But, according to the reactivity of the halogens, reactivity decreases from up to bottom of the group. F is placed above Br. Hence, F is more reactive than Br. Hence, Br can't replace F.
When C-C is having a triple bond the hybridization is sp. But I am not sure how to relate that to the linear shape.
