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One especially farishted feature of Mend...

One especially farishted feature of Mendeleev's accomplishment was his realization that some elements were missing from the table. He proposed the existence of over __________new elements in nature.

A

five

B

ten

C

four

D

eight

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The correct Answer is:
B
In Mendeleev's original periodic table, the elements after zinc `(Zn)` was arsenic `(As)` with two gaps left. Arsenic did not belong to the same chemical group as aluminium `(A1)` or as silicon `(Si)`. Arsenic was like phosphours `(P)`. That implied two unknows were missing, one like `A1` and the other like `Si`. Mendeleev proposed their exsitence and called the unknown elements `eka`-aluminium `(eka` is a Sanskrit word meaning first, thus, `ek`-aluminium would be the first element under aluminium in the same group) and `eka`-silicon.
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Read the passage and answer the following questions. Mendeleev was a Russian chemist, who contributed the most for the development of periodic table of elements wherein the elements were arranged on the basis of their fundamental property, the atomic mass and also on the similarity of chemical properties. Only 63 elements were known at his time. He arranged the 63 elements in the increasing order of the.ir atomic masses and found that there was a periodic recurrence of elements with similar physical and chemical properties. He observed that elements with similar properties fall in the same vertical column. These vertical columns are called groups and horizontal rows of elements are called periods. Mendeleev predicted the existence of certain elements not known at that time and named two of them as Eka-silicon and Eka-aluminium. Mention the group and the period of these elements in the modern periodic table.

Read the passage and answer the following questions. Mendeleev was a Russian chemist, who contributed the most for the development of periodic table of elements wherein the elements were arranged on the basis of their fundamental property, the atomic mass and also on the similarity of chemical properties. Only 63 elements were known at his time. He arranged the 63 elements in the increasing order of the.ir atomic masses and found that there was a periodic recurrence of elements with similar physical and chemical properties. He observed that elements with similar properties fall in the same vertical column. These vertical columns are called groups and horizontal rows of elements are called periods. Mendeleev predicted the existence of certain elements not known at that time and named two of them as Eka-silicon and Eka-aluminium. Name the elements which have taken the place of these elements.

Read the passage and answer the following questions. Mendeleev was a Russian chemist, who contributed the most for the development of periodic table of elements wherein the elements were arranged on the basis of their fundamental property, the atomic mass and also on the similarity of chemical properties. Only 63 elements were known at his time. He arranged the 63 elements in the increasing order of the.ir atomic masses and found that there was a periodic recurrence of elements with similar physical and chemical properties. He observed that elements with similar properties fall in the same vertical column. These vertical columns are called groups and horizontal rows of elements are called periods. Mendeleev predicted the existence of certain elements not known at that time and named two of them as Eka-silicon and Eka-aluminium. How many valence electrons are present in each one of them?

Mendeleev was a Russian chemist, who contributed the most for the development of periodic table of elements wherein the elements were arranged on the basis of their fundamental property, the atomic mass and also on the similarity of chemical properties. Only 63 elements were known at his time. He arranged the 63 elements in the increasing order of their atomic masses and found that there was a periodic recurrence of elements with similar physical and chemical properties, He observed that elements with similar properties fall in the same vertical column. These vertical columns are called groups and horizontal rows of elements are called periods. Mendeleev predicted the existence of certain elements not known at that time and named two of them as Eka-silicon and Eka-aluminium. How do we classify these newly discovered elements (eka-aluminium and eka-silicon)?

Read the passage and answer the following questions. Mendeleev was a Russian chemist, who contributed the most for the development of periodic table of elements wherein the elements were arranged on the basis of their fundamental property, the atomic mass and also on the similarity of chemical properties. Only 63 elements were known at his time. He arranged the 63 elements in the increasing order of the.ir atomic masses and found that there was a periodic recurrence of elements with similar physical and chemical properties. He observed that elements with similar properties fall in the same vertical column. These vertical columns are called groups and horizontal rows of elements are called periods. Mendeleev predicted the existence of certain elements not known at that time and named two of them as Eka-silicon and Eka-aluminium. Classify these elements as metals, non-metals and metalloids.

R SHARMA-CLASSIFICATION OF ELEMENTS AND PERIODICITY IN ELEMENTS-Follow-up Test
  1. In Mendeleev's original periodic table, there were six horixontal rows...

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  2. Mendeleev's periodic table simplified and systematized the study of th...

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  3. One especially farishted feature of Mendeleev's accomplishment was his...

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  4. Mendeleev's propdicted the properties of unknown elements.

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  5. Mebdeleev's periodic table has helped in correcting the doubtful atomi...

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  6. The position of hydrogen in Mendeleev's periodic table is not fixed bu...

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  7. In Mendeleev's table, although most of the elements were placed in the...

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  8. Since its birth in 1869, the Mendeleev periodic table has been discuss...

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  9. The empirical evolution of the periodic table reached its peak in 1913...

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  10. Which of the following gives a straight line?

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  11. Which of the following correctely describes Moseley's law?

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  12. Moden periodic law states that the properties of the elements are peri...

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  13. The physical and chemical properties of the elements denpend upton the...

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  14. The cause of periodicity in properties of the elements is the repetiti...

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  15. Which of the following numbers are called magic numbers?

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  16. The short form of the modern periodic table of the elements (also call...

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  17. In the modified Mendeleev's periodic table, the 18 vertical columns we...

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  18. In the short form of the modern periodic table, the period number corr...

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  19. In the short form of the modern periodic table, the first period conta...

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  20. In the short from of the modern periodic table,elements of both sixth ...

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