lesson 1 quiz 1

the number of element in Mendeleev's periodic table is .................element.

• 92

• 118

• 76

• 67

the nucleus of atom contains...............

• positive electrons

• negative electrons

• positive protons

• negative protons

the scientist who left vacancies in his table to fill with suitable discovered element in future ..................................

the scientist who discovered that the nucleus of atom contains positively charged proton...........................

the most important attempts to classify elements are ................................. ,.......................................&..........................

Mosely arranged element in ascending order according to their ..................................

Mendeleev arranged element in ascending order according to their …

Give reason : many attempts are made by scientists to classify of elements

give reason :Mendeleev classify the elements of each main group into 2 sub groups

(write one point) advantage of Mendeleev periodic table and disadvantages of Mendeleev's periodic table