It is a trial aimed to reduce bias during an experiment. An example would be a sugar pill, something that has no real effect so that the results of the true trial can accurately be compared. Its like a control group.
Pretty sure it’s 2, increase in strength of hurricanes
The mass of an ink pen with a triple beam balance if all the weights positioned to the right would be a maximum of 610 grams which sounds rather heavy for an ink pen but in the absence of necessary information it seems that that would have to be the answer.
Protons goes in the blank. the word can be used for both.
Answer : The correct option is, (a) Synthesis
Explanation :
Synthesis reaction : A chemical reaction where multiple substances or reactants combine to form a single product.
It is represented as,

Combustion reaction : A chemical reaction in which a hydrocarbon react with the oxygen to give product as carbon dioxide and water.
It is represented as,

Single replacement reaction : A chemical reaction in which the more reactive element replace the less reactive element.
It is represented as,

In this reaction, A is more reactive element and B is less reactive element.
Double replacement reaction : It is a type of chemical reaction where a positive cation and a negative anion of two reactants exchange places to form two new products.
It is represented as,

(X and A are the cations, Y and B are the anions)
The given reaction is, 
In this reaction, calcium combine with the chloride to form calcium chloride as a product.
Hence, the given type of reaction is a synthesis reaction.