(a) Calcium chloride Element Compound Mixture (b) Sulfur Element Compound Mixture (c) Baking powder Element Compound Mixture (d) Cytosine Element Compound Mixture

a)  Calcium chloride : Compound

(b) Sulfur : Element

(c) Baking powder:  Mixture

(d) Cytosine : Compound

Explanation:

Element is a pure substance which is composed of atoms of similar elements.It can not be decomposed into simpler constituents using chemical reactions. Example: Sulphur (S)

Compound is a pure substance which is made from atoms of different elements combined together in a fixed ratio by mass.It can be decomposed into simpler constituents using chemical reactions. Example: calcium chloride , Cytosine

Mixture is a substance which has two or more components which do not combine chemically and do not have any fixed ratio in which they are present. Example: Baking powder which is made of tartaric acid and sodium bicarbonate.