Answer: B) combustion reaction.
Explanation:
A) acid-base reaction: When an acid reacts with a base, to form metal salt and water, this type of reaction is Acid Base reaction.
Example: 
B) combustion reaction: When a hydrocarbon reacts with oxygen to produce carbon dioxide and water, this type of reaction is combustion reaction.

C) precipitation reaction: a reaction in which aqueous solution of two compounds on mixing react to form an insoluble compound which separate out as a solid are called precipitation reactions.

D) gas evolution reaction: a reaction in which one of the product is formed as a gas.

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Answer:
E) are electrically attracted to each other
Explanation:
Water molecule is polar because there is a difference in electronegativity values between hydrogen and oxygen. The hydrogen side of the molecule has a slight positive charge and the oxygen side is slightly negatively.
Positively and negatively charged ends cause water molecules to attract one another and for this reason water shows the properties mentioned in the question: cohesion, high specific heat, and high heat of vaporization.
Here we assume that disintegration has occur so the normal t½ formular will not be used
mathematically we..⅛×5600 =700
therefore it is about 700years option A