How many elements are discovered uptil now?

Answer the following questions: How many elements are there in the second and the third periods of the periodic table ?

How many nanometres is one metre ?

Who discovered viroids?

E.R. was discovered by

Who discovered ECG?

How many elements were known when Mendeleev started his work?

Answer the following questions: How many electrons are there in the outermost shell of group 18 elements?

Answer the following questions: How many electrons are there in the outermost shell of group 2 elements?