Answer:
2 a
element pure form cannot broken down
3 b
Chemical change chemical R×N
(R×N = reaction)
4c homogeneous solution
Yield = Yield (reaction yield): A measure of a chemical reaction's efficiency, as a ratio of moles of product to moles of reactant. Usually expressed as a percentage. % Yield = Moles of product.
Explanation:
Ba2+ and Cu2+, and Sr2+ and Li+
Answer: a)
: Decomposition
b)
: double displacement
c)
: Synthesis (Combination)
d)
: redox
Explanation:
Decomposition is a type of chemical reaction in which one reactant gives two or more than two products.

A double displacement reaction is one in which exchange of ions take place.

Synthesis reaction is a chemical reaction in which two reactants are combining to form one product.

Redox reaction is a type of chemical reaction in which oxidation and reduction takes place in one single reaction. The oxidation number of one element increases and the oxidation number of other element decreases.

Answer:
D.
They have a positive charge and are present in the nucleus of an atom along with the neutrons.
explanation:
Protons have a positive charge.