Periodic Classification

Grade 9 Science — Periodic Classification: 25 practice questions with instant scoring and explanations.

1. Dobereiner's Law states that the atomic mass of the middle element in a triad is approximately:
2. Which of the following is a Dobereiner triad?
3. Newlands' Law of Octaves proposed that elements repeat their properties after every:
4. The main limitation of Mendeleev's periodic table was:
5. In the modern periodic table, elements are arranged in order of increasing:
6. The vertical columns in the periodic table are called:
7. As we move down a group in the periodic table, atomic radius:
8. Which trend is correct as we move across a period from left to right?
9. The metallic character of elements:
10. Noble gases are placed in Group 18 because they have:
11. Which element has the highest electronegativity?
12. The atomic number of an element indicates the number of:
13. As we move down a group, the ionisation energy:
14. The most reactive non-metal in the periodic table is:
15. Which group contains the most reactive metals?
16. The period number of an element indicates the number of:
17. Halogens are elements that belong to:
18. The element with atomic number 17 is:
19. Electronegativity values of elements:
20. The atomic radius is largest for:
21. Which statement about ionisation energy is true?
22. An element in Period 3, Group 1 is:
23. The modern periodic table has how many groups?
24. As we move across a period, metallic character:
25. Mendeleev left gaps in his periodic table because he: