Question

Identify the pair in which the following rule for writing symbols is not needed.
“If the first two letters of the names of the elements are same, then the symbol
first letter and second or third letter of English name that they do not have in common​

Answer 1

Answer:

"If the first two letters of the names of the elements are same, then the symbol consists of

first letter and second or third letter of English name that they do not have in common

a. Argon - Ar; Arsenic - As

b. Cobalt - Co; Copper - Cu

c. Calcium - Ca; Cadmium - Cd

d. Magnesium - Mg; Manganese - Mn