Determination of atomic and isotopic mass - class-XI

Question 1 Multiple Choice (Single Answer)

There are two isotopes of an element with atomic mass $z$. Heavier one has atomic mass $z+2$ and lighter one has $z-1$, then an abundance of lighter one is:

$66.6\%$
$96.7\%$
$6.67\%$
$33.3\%$

Question 2 Multiple Choice (Single Answer)

$ _{ 17 }^{ 35 }{ Cl }$ and $ _{ 17 }^{ 37 }{ Cl }$ are two isotopes of chlorine. If average atomic mass is $35.5$ then ratio of these two isotopes is:

$35 : 37$
$1 : 3$
$3 : 1$
$2 : 1$

Question 3 Multiple Choice (Single Answer)

If isotopic distribution of $ C-12 $ and $ C-14 $ is 98 % and 2 % respectively, what would be the number of $ C-14 $ isotope in $ 12 gm $ carbon sample?

$ 1.032 \times 10^{22} $
$ 3.01 \times 10^{23} $
$ 5.88 \times 10^{23} $
$ 6.02 \times 10^{23} $

Question 4 Multiple Choice (Single Answer)

Chlorine has two naturally occurring isotopes, $^{35}Cl$ and $^{37}Cl$. If the atomic mass of Cl is 35.5 the ratio of natural abundance of $^{35}Cl$ and $^{37}Cl$ is closest to :

$ 3 : 5 $
$3 : 1$
$2 : 5 $
$4 : 1$

Question 5 Multiple Choice (Single Answer)

If an element $z$ having atomic weight $x$ exists in two isotopes of mass number $(x-1)$ and $(x+2)$ then, the percentage abundance of heavier isotopes is:

$25\%$
$66.6\%$
$33.3\%$
$20\%$

Question 6 Multiple Choice (Single Answer)

The table shows the numbers of particles present in the nuclei of four atoms or ions.

	protons	neutrons	electronic structure
$1$	$18$	$22$	$2, 8, 8$
$2$	$19$	$20$	$2, 8, 8$
$3$	$19$	$21$	$2, 8, 8, 1$
$4$	$20$	$20$	$2, 8, 8, 2$

Which two particles belong to the same element?

$1$ and $2$
$1$ and $4$
$2$ and $3$
$2$ and $4$

Question 7 Multiple Choice (Single Answer)

The average atomic mass of copper is $63.546$ amu .Natural copper consists of two iostopes: $^{63} Cu$ and $^{65} Cu$.Their natural abundances are $69.09%$ and $30.91%$ respectively. If the mass of $^{63} Cu$ isotope is $62.9298$ amu ,What is the mass of $^{65} Cu$ isotope?

64.9000
65.1233
64.9233
65.1933

Question 8 Multiple Choice (Single Answer)

Europium consists of $47.8$% Eu-$151$ and $52.2$% Eu-$153$. Calculate average atomic mass?

$152.2$
$152.1$
$151.9$
$152$

Question 9 Multiple Choice (Single Answer)

Rhenium (Re) consists of $37.1$% $185$ Re and $62.9$% $187$ Re. Calculate the relative atomic mass?

$185.6$
$185.9$
$186.3$
$186.1$

Question 10 Multiple Choice (Single Answer)

The relative abundance of two isotopes of atomic masses 85 and 87 are 75% and 25% respectively. The average atom mass of element is:

86
40
85.5
75.5

Question 11 Multiple Choice (Single Answer)

Antimony (Sb) is $57.2$% Sb-$121$ and $42.8$% Sb-$123$. Calculate the average atomic mass?

$121.6$
$120.8$
$122.4$
$121.9$

Question 12 Multiple Choice (Single Answer)

The relative atomic mass of an atom is:

measured in atomic mass units (u)
based on the mass of 1 atom of carbon-12
different for different isotopes of an element
all of the above are true

Question 13 Multiple Choice (Single Answer)

Chromium has four stable isotopes.$4.31$% Cr-$50$, $83.76$% Cr-$52$, $9.55$% Cr-$53$ and $2.38$% Cr-$54$. Calculate the relative atomic mass?

$52.1$
$52.4$
$51.8$
None

Question 14 Multiple Choice (Single Answer)

Consider a reversible isentropic expansion of $1$ mole of an ideal monoatomic gas from ${27}^{o}C$ to ${927}^{o}C$. If the initial pressure of gas was $1$ bar, the final pressure of gas becomes

$4$ bar
$8$ bar
$0.125$ bar
$0.25$ bar

Question 15 Multiple Choice (Single Answer)

Boron found in nature has an atomic weight of 10.811 and is made up of the isotopes $\displaystyle { B }^{ 10 }$ (mass 10.013 amu) and $\displaystyle { B }^{ 11 }$ (mass 11.0093). What percentage of naturally occurring boron is made up of $\displaystyle { B }^{ 10 }$ and $\displaystyle { B }^{ 11 }$, respectively?

30 : 70
25 : 75
20 : 80
15 : 85

Determination of atomic and isotopic mass - class-XI

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