Answer : The correct options are,
and 
Explanation :
Single displacement reaction : It is a type of chemical reaction in which the more reactive element displaces the less reactive element.
Option A reaction : 
It is an example of double displacement reaction because in this reaction a positive cation and a negative anion of the two reactants exchange their places to form two new products.
Option B reaction : 
It is an example of single displacement reaction.
Option C reaction : 
It is an example of combination reaction because in this reaction two reactants react to give a single product.
Option D reaction : 
It is an example of decomposition reaction because in this reaction a single reactant decomposes into two or more products.
Option E reaction : 
It is an example of single displacement reaction because in this reaction the most react element, aluminium displaces the less reactive element, hydrogen.
Hence, the options B and E are single displacement reactions.
Answer:
u just have to multiply 20x12 because its tells ya how fast the cart will be moving at 12 sec.
Explanation:because its tells ya how fast the cart will be moving at 12 sec.
The balanced chemical equation between HCl and
is:

Moles of
= 
Moles of HCl required to neutralize
:

Calculating the volume of HCl from moles and molarity:

Letter A is the characteristic of all chemical change