Which solution is a homogeneous mixture?
sand and water
salt and water
salad dressing
soil

Answer : The correct option is, salt and water  

Explanation :

Sand and water : It is a heterogeneous mixture in which the particle size of the sand and water are different. The mixture of sand and water can be separated by the physical method like filtration.

Salt and water : It is a homogeneous mixture in which the salt is completely dissolves in the water. The mixture of salt and water can not be separated by the physical method.

Salad dressing  : It is a heterogeneous mixture in which the particle size of the salad are different. The Salad dressing can be separated by the physical method.

Soil : It is a heterogeneous mixture in which the particle size of the solit are different. The soil can be separated by the physical method.

Hence, the salt and water solution is a homogeneous mixture.

2h2o2--> 2h2o + o2

this reaction is of the spontaneous decomposition of hydrogen peroxide down into water and oxygen.

add 2 molecules of hydrogen peroxide and 2 molecules of water. since oxygen is naturally diatomic, the total number of atoms of each element is now the same on both sides of the equation so it is balanced.

this may not be entirely correct but let me know.