Hello,
A physical change describes a change that does physically and does not display “chemical” signs which are signs that indicate a precipitate being formed, change in color, density, or producing gas, etc. “Tearing a piece of paper in half” is a physical change because like I said earlier it doesn’t show any chemical change signs. I hope this helps you out!
Answer: 
Explanation:-
Single replacement reaction is a chemical reaction in which more reactive element displaces the less reactive element from its salt solution.
As zinc is more reactive than copper, it could easily displace copper from its aqueous solution and thus leads to formation of zinc (II) sulfate and pure copper.
The chemical reaction can be represented as :
The phases are represented as (s) for solid sate, (l) for liquid state, (g) for gaseous state and (aq) for aqueous state.
It is two or more objects and different things that can be removed from each other.
Reactant A must be second order and reactant B first order. Overall = add them so 3rd order.
This separation technique is a 4-step procedure. First, add H₂SO₄ to the solution. Because of common ion effect, BaSO₄ will not react, only Mg(OH)₂.
Mg(OH)₂ + H₂SO₄ → MgSO₄ + 2 H₂O
The aqueous solution will now contain MgSO₄ and BaSO₄. Unlike BaSO₄, MgSO₄ is soluble in water. So, you filter out the solution. You can set aside the BaSO₄ on the filter paper. To retrieve Mg(OH)₂, add NaOH.
MgSO₄ + 2 NaOH = Mg(OH)₂ + Na₂SO₄
Na₂SO₄ is soluble in water, while Mg(OH)₂ is not. Filter this solution again. The Mg(OH)₂ is retrieved in solid form on the filter paper.
