Question

*The major demerit of Mendeleev's periodic table is that the element _______ could not be properly positioned.*

1️⃣ Helium
2️⃣ Hydrogen
3️⃣ Alluminium
4️⃣ Chlorine​

Answer 1

Answer:

hydrogen I think it is the right answer I hope it's helpful for your question please mark me as brainliest and give me thanks in my all answers

Answer 2

Explanation:

Aluminium is a correct answer.

Mark me as a brainliest.