Tag: into the history
Questions Related to into the history
An element $X$ belongs to fourth period and fifteenth group of the periodic table. Which of the following statements is true?
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It has a completely filled s-orbital and a partially filled d-orbital.
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It has completely filled s-and p-orbitals and a partially filled d-orbital.
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It has completely filled s-and p-orbitals and a half-filled d-orbital.
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It has a half-filled p-orbital and completely filled s-and d-orbitals.
Which of the following is an artificial element made by man?
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Gallium
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Iron
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Helium
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Americium
The first periodic law stated by Mendeleev was :
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there is no correlation in the properties and atomic weights of the elements
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the properties of the elements are a periodic function of their atomic numbers
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the properties of the elements are a periodic function of their atomic weights
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the properties of the elements are a periodic function of their empirical formula
A certain gas takes three times as long to effuse out as helium. Its molecular mass will be :
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27u
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36u
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64u
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9u
Some gases are taking three times as long to effuse out as helium.
The rate of effusion is always inversely proportional to the square root molecular mass.
The rate of effusion is the ratio of the volume effused to the time taken as follows.
$ \dfrac{{V} _{1}}{{t} _{1}} \times \dfrac {{t} _{2}}{{V} _{2}}$ $=\sqrt {\dfrac{{M} _{{w} _{2}}}{{M} _{{w} _{1}}}}$
Volume is same, so
$\dfrac{3}{1}= \sqrt{\dfrac{{M _{w2}}}{4}}$
So, $M _{w2} = 36\ unit.$
The molecular mass of the gas is 36 u.
So, the correct option is A.
Which of the following is not a merit of Mendeleev's periodic table?
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It helped in correcting the atomic masses of some of the elements
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He predicted the properties of some undiscovered elements and left gaps for them
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He framed the periodic table with vertical and horizontal columns and gave shape to it
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He gave separate places to isotopes in his periodic table
Numbering of groups as 1, 2, ........... 18 was adopted by IUPAC in :
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1986
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1906
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1908
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1988
Two earlier group number systems exist: CAS (Chemical Abstracts Service) and old IUPAC. Both use numerals (Arabic or Roman) and letters A and B. In 1988 the new system simply numbers the groups increasingly from left to right on the standard periodic table.
Nobel gases were included in Mendeleev's periodic table in the:
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1st group
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7th group
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8th group
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none of these
Mendeleevs Periodic Table:
Elements are arranged in the periodic table in the increasing order of their relative atomic masses.
Mendeleev divided his periodic table in eight groups and seven periods.
Groups from I to VII are meant for normal elements and group VIII is for transition elements.
Groups from I to VII have been divided in two sub groups, while group VIII is meant for three elements.
Periods from 4th to 7th have been divided in two series: 1st series and 2nd series.
Elements having similar properties have been kept in the same group. For example; lithium, potassium, rubidium, etc. are in 1st group.
Whose name is associated with the development of periodic table ?
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Newlands
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Mendeleev
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Dalton
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Doberiener
Mendeleeve is credited with the development of his periodic table to illustrate periodic trends of known elements and predicted properties of unknown elements also.
Total number of groups in Mendeleev's table is:
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$8$
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$9$
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$7$
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$10$
Mendeleev’s Periodic table says that the periodic function of their relative atomic masses. Mendeleev arranged all the 63 elements in it. These only were discovered in his time. These are in the order of their increasing relative atomic masses in a tabular form. It is the Periodic Table. He had the table with eight columns and seven rows. The columns are the groups whereas rows are the periods.
Hence, the correct option is A.
The number of elements known in Mendeleev's presented periodic table is:
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$50$
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$90$
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$63$
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$102$
After the rejection of Newlands Octave
Law, Mendeleev Periodic table came into existence. In Mendeleev’s periodic
table, elements were placed based on the atomic mass, and chemical
properties. During Mendeleev’s work, only 63 elements were found. After
studying the properties of all elements, he found that the properties of
elements were related to atomic mass.
Hence, the correct option is C.