What were the criteria used by Mendeleev in creating his Periodic Table ?

Besides gallium, which other elements have since been discovered that were left by Mendeleev's in his Periodic Table ? (any two)

What property did Mendeleev use to classify elements in his periodic table?

What is the criteria to decide a best fuel ?

What are the limitations of Mendeleev’s periodic table ? How could the modern periodic table overcome the limitations of Mendeleev’s table?

What are the criteria for classifying plants ?

(a) What property do all elements in the same column of the Periodic Table as boron have in common ? (b) What property do all elements in the same column of the Periodic Table as fluorine have in common ?

How could the Modern Periodic Table remove various anomalies of Mendeleev's Periodic Table ?

What criteria do we use to decide whether something is alive?

How many periods are there in the mendeleev 's periodic table ?

What is a period in modern periodic table ?