Question

1. There are some vacant places in the Mendeleev's periodic table.
In some of these places the atomic masses are seen to be
predicted. Enlist three of these predicted atomic masses along
with their group and period.
2. Due to uncertainty in the names of some of the elements, a
question mark is indicated before the symbol in the Mendeleev's
periodic table. What are such symbols?​

Answer 1

Answer:

hope it helps you mark as brainliest..........ssc class 10 page no 18

Answer 2

Explanation:

ANSWER IN ATTACHMENT FILE