Periodic Classification of Elements class 10th

Class 10th CBSE Chemistry 

Very important questions and answers for BOARD exam.
Very short type question

 1. What was the basis of classification of elements in the Mendeleev's periodic table.

2.Name the scientist who for the first time divided elements into metals and non-metals.

3. Name the three elements for which Mendeleev left gaps in the periodic table.

4 Name a group of elements which was not known at the time when Mendeleev  gave his periodic table .

5. Name an anomalous pair of elements in Mendeleev’s periodic table.

6 Name the missing elements in the triad of Li and K.

7. Which element was named as ‘Eka-silicon in Mendeleev’s periodic table?

8. Elements X and Y obey Newland’s Law of Octaves .How many elements are present between these two elements?

9. Name three alkali metals which form a Dobereiner triad?

10. Among the elements F, Cl, Br and I, which does not fit into the triad?

             Answers

1. Atomic mass 

2. Lavoisier 

3. Scandium (Sc), gallium (Ga) and gennzinium (Ge). 

4. Noble or inert gases. 

5. Anomalous pair of elements : In Mendeleev’s periodic table, Cobalt with higher atomic mass (58.93u) has been placed before nickel (Ni) with a lower atomic mass (58.93u)

6. Sodium (Na) 

7. Germanium (Ge) 

8. Six elements 

9. Lithium (Li). sodium(Na) and potassium (K). 

10. Fluorine (F)