Question

Very Short Answer (VSA) Tupe Questions
(1 Mark each
1. Among the coming elements El Brand I which 6. why does icon has valency and chlorine 12
does not fit in a triad?
7. Out of the three elements Ca. Mg. So which one will
2. What is the basis for the dawafication of modern
have atom of Nicotine?
periodic table?
8 Nisan element with atomic number=20. What will be
3. Name the two elements whose valencia are equal to
the formula of its chloride?
their group number
9. A metal belongs to 15th group in the modern
4. Which element come after richt) him in the periodic table write the valency of the metal
periodic table?
10. Out of li. Cand which form the most basic oxide
5. Calcium is an element with atomic number=20. Is it
and which form the most acidic oxide?
more reactive or less reactive than Mg?
Short Answer (SA) Tupe I Questions
11. Initially it was believed that atomic mass of berylum
was 13. But Mendele suggested that its atomic miss
should be
Was Mendeles secoestion correct?
() Eow had he reached to this conclusion?
12. Write the trend of atomic sine along a group and a
period in the modern periodic table.
13. An element X belongs to the second period and
group 15 of the periodic table. Find our
(i) the number of valence electrons in its atoms.
(3) valency of the element
(2 Maris each)
( What is the nature of oxide of Bil oxide of & is
amphoteric?
Give reason for your answer.
17. Write reason for the following Number in parenthe
is atomic number of the substance)
) Lithium ) and sodium (1) are considered a
active metals
() Fluorine (9) is more reactive than chlorine 17e​

Answer 1

Answer:

(a) Al has the highest valency of 3. As it belongs to group IIIA, it has 3 electrons in its valence shell. So, its valency is 3.

(b) Na has the largest atomic radius as the atomic radius decreases across the period.

(c) As we move from left to right in a period the chemical reactivity of a metal decreases and of non-metal increases. Here given are metals and hence Na is most reactive as it is the first element of period 3.

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