Answer:
2:A handwarmer gets warm when it is opened and exposed to air.
3:Propane ignites to heat a grill.
4:Cotton is dyed red to make a dress.
Explanation:
The definition of a chemical property is when a property of characteristic of a substance that is <em><u>observed</u></em> during a reaction in which a chemical has been changed
Answer:
false, true, false - In reality stirring increases the speed of dissolving.
Divide velocity by the wavelength.
Answer : Option 4) 
Explanation : is the only sample of matter which can be classified as a solution. As the solution can be defined as a liquid mixture which contains a minor component (the solute) that is uniformly distributed within the major component (the solvent).
In this case, the solute is 
which is dissolved in water which acts as an solvent. Also, it has a subscript which is aq. which means aqueous, is often given to the solution in which the solvent is water.
Therefore, is the correct answer.
Answer is: 4) The same subscripts are on each side of the equation.
For example, balanced chemical reaction:
2Mg + O₂ → 2MgO.
1) The same number of atoms is on each side of the equation: two magnesium atoms and two oxgen atoms.
2) The formulas for all substances are correct: in magnesium oxide (MgO), magnesium has oxidation number +2 and oxygen -2, so formula is good, because compound must be neutral.
3) The same mass is represented on each side of the equation: because there is same number of atoms, the mass is the same.
4) The same subscripts are on each side of the equation: oxygen does not have same subscripts.
