The average speed of the blocks are 0.36 m/s.
Explanation:
Average speed is defined as the ratio of distance covered per unit time. So if it is said that blocks are pulled to 0.9 m in the right side. This means the blocks cover a distance of 0.9 m from the origin and that distance is covered in 2.5 s. Thus, the average speed can be calculated from the change in speed with respect to time. As at time t = 0 , the speed is also zero, and at time t = 2.5 s , the speed will be
Since, in this case, the speed is equal to the average speed of blocks. So the average speed of the blocks will be 0.36 m/s.
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.
Answer:
water is not the chemical hope ur help
Each unit of pH represents a change by a factor of 10. Thus in a pH of 5, there would be 100x the concentration of Hydrogen ions in solution.
The correct option would be 2.
You could say that hydrogen and Oxygen molecules are similar in that their chemical formula is H2 and O2. That means there are 2 "atoms" per molecule. I don't know how to put water into this because water molecules are quite different from H2 and O2. Even the intramolecular forces are quite different.
H2 and O2 are different in their masses per molecule.One is quite a bit heavier than the other. They can be quite explosive if they are put in the same container. I once heard a NASA engineer say that Hydrogen is a "real snake" to handle. It is used for rocket fuel. Both are compressed a great deal.