Mass of sodium is 23 and mass of fluirine is 19 there mass of NaF is 42
42 g = 1 mole therefor 4.5 moles will have
4.5 × 42 = 189 g
Answer:
Paris climate agreement of 2015
Explanation:
In the year 2015, global leaders seeking to join forces to combat the ever increasing emissions of green house gases which is having a bad influence on our prevailing world climate met in Paris in 2015, although the treaty became effective in the year 2016.
There are 195 signatories to the treaty. The Paris Agreement's long-term temperature goal is to keep the increase in global average temperature to well below 2 °C above pre-industrial levels; and to pursue efforts to limit the increase to 1.5 °C, recognizing that this would substantially reduce the risks and impacts of climate change.
Answer : The correct option is, (D)
Explanation :
Option A reaction : 
It is a combustion reaction. A reaction in which a hydrocarbon react with the oxygen to give product as carbon dioxide and water.
Option B reaction : 
It is a combination reaction. A reaction in which the two or more reactants react to give a product.
Option C reaction : 
It is a decomposition reaction. A reaction in which a reactant decomposes to form two or more products.
Option D reaction : 
It is a single displacement reaction. It is a reaction in which the more reactive element displace the less reactive element. In this reaction, most reactive element chlorine displaces the less reactive element bromine.
Hence, the correct option is, (D)