Answer: 
Explanation:
A single displacement reaction is one in which a more reactive element displaces a less reactive element from its salt solution. Thus one element should be different from another element.

Synthesis reaction is defined as the reaction where substances combine in their elemental state to form a single compound.
Decomposition reaction is defined as the reaction where a single substance breaks down into two or more simpler substances.

Combustion is a type of chemical reaction in which hydrocarbons burn in the presence of oxygen to form carbon dioxide and water along with heat.

Answer:
B
Explanation:
B It’s a physical change because the water and the salt kept their original properties.
Answer:
Relative atomic mass or atomic weight is a dimensionless physical quantity defined as the ratio of the average mass of atoms of a chemical element in a given sample to the atomic mass constant. The atomic mass constant is defined as being 1/12 of the mass of a carbon-12 atom.
Explanation:
Sodium Chloride or NaCl is made up of two elements, sodium (or Na) and chlorine (or Cl). A molecule of sodium chloride, NaCl, consists of one atom each of sodium and chlorine. Hence, each molecule of NaCl has 2 atoms total.
Answer:
Explanation has been given below.
Explanation:
- A buffer consists of either of a weak acid along with it's conjugate base or a weak base along with it's conjugate acid.
- Let's consider a buffer consists of a weak acid along with it's conjugate base
- If we add an acid to this buffer then conjugate base gets protonated and converted to corresponding weak acid. So effect of addition of acid gets neutralized by forming weak acid rather than increase in concentration of proton in solution.
- If we add a base to this buffer then weak acid gets converted to corresponding conjugate base. So effect of addition of base gets neutralized by forming conjugate base rather than in crease in concentration of hydroxyl ion in solution.