The question is incomplete, complete question is:
When copper(I) sulfide is partially roasted in air (reaction with oxygen), copper(I) sulfite is formed first. subsequently, upon heating, the copper sulfite thermally decomposes to copper(I) oxide and sulfur dioxide. Write balanced chemical equations for these two reactions.
Answer:
The balanced chemical equations for these two reactions:


Explanation:
On partial roasting of copper sulfide in an air. The balanced chemical reaction is given as:

On further heating of copper(I) sulfite it get decomposes into copper oxide and sulfur dioxide. The balanced chemical reaction is given as:

An ionic compound is made up of two or more metals and non-metals
A covalent compound is made up of two or more non-metals.
Therefore calcium (non-metal) and chlorine(non-metal) make up a covalent compound
Correct Answer: Mixture will be heterogeneous
Reason:
The mixture is said to be homogenous, if it contains single phase, On other hand, heterogenous system has, multiple phases. When, oil and vinegar are mixed together, on standing, the two liquids separates out as different phases. Hence, the mixture will be refereed as heterogeneous.
The number to the left of a chemical formula is called coefficients
Explanation
Coefficient is the number in front of a chemical formula.
It tell how many molecules of a given formula that are involved in a chemical reaction.
in 2H+O→ H2O the coefficient are 2,1,1
that is, 2 in front of H2
1 in front of O
1 in front of H2O