Which of the following is an example of a compounds? Select one:
a. Cu
b. CaCl2
c. Na
d. Nd

b.CaCl2

Explanation:

A compound is  a substance resulting when two or more elements  are are chemically bonded together either ionically or covalently in a fixed ratio.

From the given options we can see that the only compound there  is CaCl2 which is an ionic compound in the fixed  ratio of one calcium ion to two chloride ions.

Other options , Cu,Na and Nd are merely pure substance---Elements

c is having 4 valence electrons and is bonded to three hydrogens and one sulphur atom, therefore, the number of bond pair is equal to four. as all the valence electrons are used in forming the bonds so, there is no lone pair left on carbon.

s is having 6 valence electrons and is bonded to one other sulfur atom and one carbon atom, therefore, the number of bond pair is equal to 2. as only two valence electrons are used in forming the bonds so, four electrons are left. therefore, two lone pairs are present on s.