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प्रश्न
Right or wrong sentence.
The elements lithium and beryllium are in the same period because their valencies are similar.
विकल्प
Right
Wrong
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उत्तर
The given sentence is wrong.
Explanation:
- Lithium and beryllium are in the same period because they have the same number of electron shells (they are both in period 2), not because their valencies are similar.
- Valency depends on the number of electrons in the outermost shell; Li has valency 1 while Be has valency 2, so their valencies are different.
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संबंधित प्रश्न
An element has its electron configuration as 2, 8, 2. Now answer the following question.
a. What is the atomic number of this element?
b. What is the group of this element?
c. To which period does this element belong?
d. With which of the following elements would this element resemble? (Atomic numbers are given in the brackets)
N(7), Be(4), Ar(18), Cl(17)
Write down the electronic configuration of the following elements from the given atomic numbers. Answer the following question with explanation.
1H, 7N, 20Ca, 16S, 4Be, 18Ar Which of these elements belong to the second group?
An element has its electron configuration as 2,8,2. Now answer the following questions.
i. What is the atomic number of this element?
ii. What is the valency of this element?
iii. What is the group of this element?
iv. To which period does this element belong?
v. With which of the following elements would this element resemble?
`_7N , _4Be , _18Ar , _17CL`
An element has its electron configuration as 2, 8, 2. Now answer the following question.
With which of the following elements would this element resemble?
(Atomic numbers are given in the brackets)
N(7), Be(4), Ar(18), Cl(17)
Find the odd one out and give its explanation.
Find the odd one out and give its explanation.
Answer the following question in one sentence.
Write the name of the noble gas having 2 electrons in its valence shell.
Match the columns.
| Column A | Column B |
| 1) s -block | a) Lanthanides and actinides |
| 2) p -block | b) Group 3 to 12 |
| 3) d -block | c) Group 1, 2 |
| 4) f -block | d) Group 13 to 18 |
| e) Zero group |
Match the columns.
| Column A | Column B |
| 1) Alkaline earth metals | a) Group 18 |
| 2) Alkali metals | b) Group 17 |
| 3) Halogen | c) Group 2 |
| 4) Noble gas | d) Group 1 |
| e) Group 14 |
Right or wrong sentence.
The valency of the elements in group 2 is 1.
Beryllium and calcium are alkaline earth metals.
Complete the following chart.
| Shell | n | 2n2 | Electron holding capacity |
| K | 2 × 12 | 2 | |
| L | 2 | 8 | |
| 3 | 2 × 32 | 18 | |
| N | 4 | 2 × 42 |
Find the period in which these elements can be placed.
4Be, 17Cl, 2He, 13Al
Write name of elements, symbol, atomic number, electronic configuration of second period in modern periodic table?
Identify periods of elements and blocks of elements from given electronic configuration?
- 2, 8, 2
- 2, 8, 7
- 2, 1
Observe the given chart and answer the questions given below.
| Element | A | B | C | D |
| Electronic configuration | 2, 1 | 2, 8 | 2, 8, 1 | 2, 8, 8 |
- Which elements are in the same row?
- Which elements have the same column?
- Which elements are in the 18th column?
- Which element is more reactive among A and C?
- Which of the following elements A or B will form compounds?
Observe the periodic table given below and write the answers of the questions.
- Write the name and valencies of the elements in 3rd row.
- Classify the elements in this row as metal, nonmetal and metalloids.
- Which block does nonmetals belong to?
- Write name of any two metalloid elements.
Make a chart which shows the name of the element, valency, atomic number, electronic configuration in the 2nd row of the modern periodic table and arrange these elements in ascending order of atomic mass.
