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प्रश्न
Fill in the blank and rewrite the completed statement:
________ group in the periodic table contains elements that are all gases at room temperature.
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उत्तर
The 18th group in the periodic table contains elements that are all gases at room temperature.
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संबंधित प्रश्न
The elements 4Be, 12Mg and 20Ca, each having two valence electrons in their valence shells, are in periods 2, 3 and 4 respectively of the modern periodic table. Answer the following questions associated with these elements, giving reason in each case:
(a) In which group should they be?
(b) Which one of them is least reactive?
(c) Which one of them has the largest atomic size?
Based on the group valency of elements state the formula lot the following giving justification for each :-
(i) Oxides of 1st group elements,
(ii) Halides of the elements of group 13, and
(iii) Compounds formed when an element of group 2 combines with, an element of group 16.
Classify the following elements into metals, non-metals and metalliods
As, C, Hg, Mg, S, Si
An element with the atomic number 19 will most likely combine chemically with the element whose atomic number is ______.
The following table shows the electronic configuration of the elements W, X, Y, Z:
| Element | w | x | y | z |
| Electronic configurations |
2, 8, 1 | 2, 8, 7 | 2, 5 | 1 |
Answer the following questions based on the table above:
1) What type of Bond is formed between :
a) W and X
b) Y and Z
2) What is the formula of the compound formed between :
a) X and Z
b) W and X
Calculate the mass of Calcium that will contain the same number of the atom as are present in 3.2 gm of Sulphur.
[Atomic masses: S=32, Ca=40]
An element Z has atomic number 16. Answer the following questions on Z:
1) State the period and group to which Z belongs
2) Is Z a metal or a non-metal?
3) State the formula between Z and hydrogen
4) What kind of a compound is this?
Fill in the blank in the following statement:
In going across a period (right to left) in periodic table, the atomic size of the atom ...............
An element X belongs to group 2 and another element Y belongs to group 15 of the periodic table:
(a) What is the number of valence electron in X?
(b) What is the valency of X?
(c) What is the number of valence electrons in Y?
(d) What is the valency of Y?
Explain how you have arrived at your answers.
How does the electropositive character of elements change on going down in a group of the periodic table?
How does Chemical reactivity of elements change on going from left to right in a period of the periodic table?
Give example in support of your answer.
State one reason for keeping fluorine and chlorine in the same of the periodic table.
How does the tendency to lose electrons change as we go down in group 1 of the periodic table? Why does it change this way?
Explain why, the properties of elements are repeated after 2, 8, 18 and 32 elements in the periodic table.
Five elements A, B, C, D and E have atomic numbers of 2, 3, 7, 10 and 18 respectively. The elements which belong to the same period of the periodic table are:
(a) A, B, C
(b) B, C, D
(c) A, D, E
(d) B, D, E
The atomic numbers of three elements A, B and C are given below:
| Element | Atomic number |
| A | 5 |
| B | 7 |
| C | 10 |
(i) Which element belongs to group 18?
(ii) Which element belongs to group 15?
(iii) Which element belongs to group 13?
(iv) To which period/periods do these elements belong?
Periodicity is observed due to the similar ______.
What do you understand by periodicity?
Name two elements you would expect to show chemical reactions similar to calcium. What is the basis of your choice?
Why fluorine has higher E.N. than chorine?
An element X belong to 3rd periods and group II of the periodic table state:
the number of valence electrons,
An element X belong to 3rd periods and group II of the periodic table state:
the valency,
Complete the following sentences.
The properties of the elements are a periodic function of their …………… (atomic number, mass number, reative atomic mass).
Complete the following sentences
The similarities in the properties of a group of elements are because they have the same …………………
First ionization enthalpy of two elements X and Y are 500 KJ mol-1 and 375 KJ mol-1 respectively. Comment about their relative position in a group as well as in a period.
What is meant by periodicity of elements?
Fill in the blank
There are ______ groups and ______ periods in the modern form of periodic table.
Arrange the following in increasing order of property indicated
SiO2, P2O5, SO3, Cl2O7 (acidic nature)
The following questions refer to the Periodic Table.
Name the first and last element in period 2.
Arrange the following as per instruction given in the bracket.
Cs, Na, Li, K, Rb (decreasing electronegativity)
An element belongs to the third period and Group IIIA (13) of the periodic table. State: the number of valence electrons,
Moving left to right in the second period, the number of valence electrons _____.
An element A has 2 electrons in its fourth shell. State:
is it a metal or non-metal
Based on the group valency of element write the molecular formula of the following compound giving justification:
Compound formed when an element A of group 2 combines with an element B of group seventeen.
Name or state following with reference to the element of the first three periods of the periodic table.
A non-metal in period 2 which is tetravalent.
Fill in the blanks from the words A to F given below’.
A: Decreases
B: Increases
C: Remains same
D: Increases by one
E: Electropositive
F: Electronegative
Across a period from left to right in the Modern Periodic Table.
No. of electron shells _________; No. of valence electrons __________: Electronegativity increases Character of elements changes from electropositive to ________.
