Explanation:
The chemical formula of an ionic compound can be written by using the symbols of the respective cations and anions.
The overall charge on the molecule should be zero.
Hence, the total charge of cations=total charge of anions.
The symbols of the given molecules are shown below:
sodium chloride ---- NaCl
magnesium chloride ---
calcium oxide ---- CaO
lithium phosphide----
aluminum sulfide -----
calcium nitride----
The correct answer is:
b: Heluim
Explanation:
The caffeine contains:
carbon , nitrogen , oxygen ,
hydrogen.
Caffeine is a primary nervous system energizer of the methylxanthine class. It is the world's most universally consumed psychoactive drug. Unlike many other psychoactive elements, it is fair and unlimited in nearly all parts of the world. Caffeine can be arranged as an alkaloid, a term used for substances originated as end results of nitrogen metabolism in some plants.
C. no difference in the electronegativity of oxygen and hydrogen