10.) Which of the following subatomic particles makes up the nucleus of an atom?

A. electrons and protons
B. electrons and neutrons
C. protons and neutrons
D. neutrons

11.) What was the contribution of MENDELEEV in developing the periodic table?

A. discovering protons
B. discovering Mendelevium
C. creating today's atomic model
D. publishing the first periodic table

12.) What do you call each column of the periodic table?

A. a group
B. a period
C. an isotope
D. an element

13.) What do you call each raw of the periodic table?

A. a group
B. a period
C. an isotope
D. an element

14.)According to the periodic law, how do elements that have similar properties appear?

A. to the left of each other
B. to the right of each other
C. at very tenth element
D. at regular intervals periodically

15.) Why do elements within the same group in the periodic table have similar properties?

A. same number of ions
B. same number of neutrons
C. same number of protons
D. same number of valence electrons
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