Answer:
Inside it's usually warm so when you open a door to outside which is cold a cold front and a warm front will be exposed to each other cold will win usually since cold goes below the warm front.
Explanation:
The chemical reaction in which number of atoms of each element present in the reactant side is equal to the number of atoms of that element in product side, such reactions are said to be a balanced chemical reaction.
The chemical symbol for sodium is
.
The chemical symbol for fluorine gas is
.
The chemical symbol for sodium fluoride is 
The sodium fluoride is prepared from the reaction between sodium metal and fluorine gas can be written as:

The above reaction is not balanced as the number of fluorine atoms are not same on reactant and product side. So, in order to balance the reaction we will multiply
with 2 on reactant side and
with 2 on product side. Thus, the balanced reaction will be:

Thus, the balanced chemical equation is
.
Answer:
The US surgeon general's 1964 report declared that smoking cigarettes was linked to cancer
The average global temperature of the Earth has increased by almost two degrees in the last century.
Explanation:
Polar solvents
hope it helps