Attempts of elements classification

Mendleev classified the elements of each group into ………sub-groups

• 2
• 3
• 4
• 5

The scientist who left vacancies in his table to be filled with suitable discovered elements in future is …….

• Mosely
• Rutherford
• Bohr
• Mendleev

The nucleus of the atom contains……..

• positive electrons
• negative electrons
• negative protons
• positive protons

The scientist, who discovered that the nucleus of atom contains positively charged protons is………

• Bohr
• Mendeleev
• Rutherford
• Mosely

The scientist ……….had discovered the main energy levels.

• Bohr
• Mendeleev
• Hofmann
• Mosely

The number of energy levels in the heaviest known atom is……levels

• 5
• 7
• 8
• 10

The number of known elements in the modern periodic table till now is……

• 216
• 118
• 316
• 16

The number of elements which exists in nature is ………..

• 29
• 118
• 92
• 102

The moden periodic table consists of ………horizintal periods

• 7
• 10
• 14
• 18

The moden periodic table consists of ………vertical groups

• 7
• 10
• 14
• 18