What is the number of periods and (RBSESolutions.com) groups in the modern periodic
A. 7 and 18
B. 9 and 18
C. 7 and 20
D. 9 and 20
Answer:C
What is the number of periods and (RBSESolutions.com) groups in the modern periodic
A. 7 and 18 B. 9 and 18 C. 7 and 20 D. 9 and 20