Answer:
A = 2
B = 1
Step-by-step explanation:
The atomic number of lithium is 3.
Its atomic mass is 7 amu.
It is present in group group 1.
It has one valance electron.
Lithium is alkali metal it form salts.
It is silvery soft metal. It has lowest density as compared to all other metals.
It react vigorously with water.
It is used in rechargeable batteries which are used in camera, mobile, laptops etc.
The electronic configuration of Li:
Li₃ = 1s² 2s¹
Thus,
A = 2
B = 1