Answer:
Mendeleev had left the noble gases out of his periodic table.
Explanation:
Mendeleev's periodic table is pictured in the image attached to the question.
Mendeleev's table obviously lacked the noble gases. The reason for this grave omission is simple; the noble gases were not known as at the time when he formulated his periodic table. There weren't any known elements whose properties were similar to the properties of the noble gases. This would have lead him to suspect their existence.
The correct answer are:
#1. The measure of gravity on earth determines our weight
#2. The closer an object is to the center of earth, the greater the gravitational force on that object.
#3. Objects in a free fall are constantly picking up speed as they fall back to earth is true.
Brainliest please!
Here's the numbers
H = +1
Cl = -1
4 elements are classified in group 4 like titanium, zirconium, hafnium and ruthorfordium
