### JEE Mains Previous Years Questions with Solutions

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1

### AIEEE 2003

According to the Periodic Law of elements, the variation in properties of elements is related to their
A
nuclear masses
B
atomic numbers
C
nuclear neutron-proton number ratios
D
atomic masses

## Explanation

According to modified modern periodic law, physical and chemical properties of the elements are periodic functions of their atomic numbers.
2

### AIEEE 2002

$C{e^{ + 3}},\,\,L{a^{ + 3}},\,\,P{m^{ + 3}}\,\,$ and $Y{b^{ + 3}}\,\,$ have ionic radial in the increasing order as
A
$L{a^{ + 3}}\,\, < C{e^{ + 3}}\,\, < P{m^{ + 3}}\,\, < Y{b^{ + 3}}$
B
$Y{b^{ + 3}}\,\, < P{m^{ + 3}}\,\, < C{e^{ + 3}}\,<\,L{a^{ + 3}}$
C
$L{a^{ + 3}}\,\, = C{e^{ + 3}}\,\, < P{m^{ + 3}}\,\, < Y{b^{ + 3}}$
D
$Y{b^{ + 3}}\,\, < P{m^{ + 3}}\,\, < L{a^{ + 3}}\,\, < C{e^{ + 3}}$

## Explanation

Here $C{e^{ + 3}},\,\,P{m^{ + 3}},\,\,Y{b^{ + 3}}$ are from lanthanide series.

$L{a^{ + 3}}$ atomic number is $57.$ This is a $d$ block element but all the property of $La$ is similar to lanthanides. It is present before $Ce.$

As we know in lanthanides the radius of elements decreases from left to right of periodic table.

So, order will be $L{a^{ + 3}} > C{e^{ + 3}} > P{m^{ + 3}} > Y{b^{ + 3}}$
3

### AIEEE 2002

The correct order of ionic radius is
A
$Ce > Sm > Tb > Lu$
B
$Lu > Tb > Sm > Ce$
C
$Tb > Lu > Sm > Ce$
D
$Sm > Tb > Lu > Ce$

## Explanation

Those are the elements of lanthanides series.

In lanthanide series the extra electron is added in $4f$ subshell and we know in periodic table from left to right the effective nuclear charge increases as electron is added so the size of elements will decreases.

So, the correct order is $Ce > Sm > Tb > Lu.$