Structure 1.2.3—Mass spectra. Mass spectra are used to determine the relative atomic masses of elements from their isotopic composition. Interpret mass spectra in terms of identity and relative abundance of isotopes.

Mass spectrometry analysis of a sample of iron gave the following results:

Calculate the relative atomic mass, A_r, of this sample of iron to two decimal places.

Mass spectrometry analysis of a sample of iron gave the following results:

Calculate the relative atomic mass, A_r, of this sample of iron to two decimal places.

Mass spectrometry analysis of a sample of iron gave the following results:

Calculate the relative atomic mass, A_r, of this sample of iron to two decimal places.

Mass spectrometry analysis of a sample of iron gave the following results:

Calculate the relative atomic mass, A_r, of this sample of iron to two decimal places.

Mass spectrometry analysis of a sample of iron gave the following results:

Calculate the relative atomic mass, A_r, of this sample of iron to two decimal places.

Mass spectrometry analysis of a sample of iron gave the following results:

Calculate the relative atomic mass, A_r, of this sample of iron to two decimal places.

What is the relative atomic mass, $A_{\mathrm{r}}$, of an element with this mass spectrum?

A.  $24.0$

B.  $24.3$

C.  $24.9$

D.  $25.0$

What is the relative atomic mass, $A_{\mathrm{r}}$, of an element with this mass spectrum?

A.  $24.0$

B.  $24.3$

C.  $24.9$

D.  $25.0$

What is the relative atomic mass, $A_{\mathrm{r}}$, of an element with this mass spectrum?

A.  $24.0$

B.  $24.3$

C.  $24.9$

D.  $25.0$

What is the relative atomic mass, $A_{\mathrm{r}}$, of an element with this mass spectrum?

A.  $24.0$

B.  $24.3$

C.  $24.9$

D.  $25.0$

What is the relative molecular mass of bromine, according to the following mass spectrum?

NIST Mass Spectrometry Data Center Collection © 2014 copyright by the U.S. Secretary of Commerce
on behalf of the United States of America. All rights reserved.

A.  $\frac{158\times 52+160\times 100+162\times 48}{52+100+48}$

B.  $\frac{158\times 52+160\times 100+162\times 48}{158+160+162}$

C.  $\frac{79\times 11+81\times 11+158\times 52+160\times 100+162\times 48}{11+11+52+100+48}$

D.  $\frac{79\times 11+81\times 11}{11+11}$

What is the relative molecular mass of bromine, according to the following mass spectrum?

NIST Mass Spectrometry Data Center Collection © 2014 copyright by the U.S. Secretary of Commerce
on behalf of the United States of America. All rights reserved.

A.  $\frac{158\times 52+160\times 100+162\times 48}{52+100+48}$

B.  $\frac{158\times 52+160\times 100+162\times 48}{158+160+162}$

C.  $\frac{79\times 11+81\times 11+158\times 52+160\times 100+162\times 48}{11+11+52+100+48}$

D.  $\frac{79\times 11+81\times 11}{11+11}$

What is the relative molecular mass of bromine, according to the following mass spectrum?

NIST Mass Spectrometry Data Center Collection © 2014 copyright by the U.S. Secretary of Commerce
on behalf of the United States of America. All rights reserved.

A.  $\frac{158\times 52+160\times 100+162\times 48}{52+100+48}$

B.  $\frac{158\times 52+160\times 100+162\times 48}{158+160+162}$

C.  $\frac{79\times 11+81\times 11+158\times 52+160\times 100+162\times 48}{11+11+52+100+48}$

D.  $\frac{79\times 11+81\times 11}{11+11}$

What is the relative molecular mass of bromine, according to the following mass spectrum?

NIST Mass Spectrometry Data Center Collection © 2014 copyright by the U.S. Secretary of Commerce
on behalf of the United States of America. All rights reserved.

A.  $\frac{158\times 52+160\times 100+162\times 48}{52+100+48}$

B.  $\frac{158\times 52+160\times 100+162\times 48}{158+160+162}$

C.  $\frac{79\times 11+81\times 11+158\times 52+160\times 100+162\times 48}{11+11+52+100+48}$

D.  $\frac{79\times 11+81\times 11}{11+11}$

What can be deduced from the mass spectrum of CH₃COCH₂CH₂CH₃?

NIST Mass Spectrometry Data Center Collection (C) 2021 copyright by the U.S. Secretary of Commerce on behalf of the United States of America. All rights reserved. 2-Pentanone Mass Spectrum, MS Number 291264. [graph] Available at: https://webbook.nist.gov/cgi/cbook.cgi?ID=C107879&Units=SI&Mask=200#Mass-Spec2-pentanone [Accessed 4 May 2020]. source adapted.

A.  The molar mass is 43 g mol⁻¹.

B.  The atoms have many isotopes.

C.  The most likely bond to break is C–C between carbons 2 and 3.

D.  The signal with the largest mass is due to the oxidation of the ketone in the spectrometer.

What can be deduced from the mass spectrum of CH₃COCH₂CH₂CH₃?

NIST Mass Spectrometry Data Center Collection (C) 2021 copyright by the U.S. Secretary of Commerce on behalf of the United States of America. All rights reserved. 2-Pentanone Mass Spectrum, MS Number 291264. [graph] Available at: https://webbook.nist.gov/cgi/cbook.cgi?ID=C107879&Units=SI&Mask=200#Mass-Spec2-pentanone [Accessed 4 May 2020]. source adapted.

A.  The molar mass is 43 g mol⁻¹.

B.  The atoms have many isotopes.

C.  The most likely bond to break is C–C between carbons 2 and 3.

D.  The signal with the largest mass is due to the oxidation of the ketone in the spectrometer.

What can be deduced from the mass spectrum of CH₃COCH₂CH₂CH₃?

NIST Mass Spectrometry Data Center Collection (C) 2021 copyright by the U.S. Secretary of Commerce on behalf of the United States of America. All rights reserved. 2-Pentanone Mass Spectrum, MS Number 291264. [graph] Available at: https://webbook.nist.gov/cgi/cbook.cgi?ID=C107879&Units=SI&Mask=200#Mass-Spec2-pentanone [Accessed 4 May 2020]. source adapted.

A.  The molar mass is 43 g mol⁻¹.

B.  The atoms have many isotopes.

C.  The most likely bond to break is C–C between carbons 2 and 3.

D.  The signal with the largest mass is due to the oxidation of the ketone in the spectrometer.

What can be deduced from the mass spectrum of CH₃COCH₂CH₂CH₃?

NIST Mass Spectrometry Data Center Collection (C) 2021 copyright by the U.S. Secretary of Commerce on behalf of the United States of America. All rights reserved. 2-Pentanone Mass Spectrum, MS Number 291264. [graph] Available at: https://webbook.nist.gov/cgi/cbook.cgi?ID=C107879&Units=SI&Mask=200#Mass-Spec2-pentanone [Accessed 4 May 2020]. source adapted.

A.  The molar mass is 43 g mol⁻¹.

B.  The atoms have many isotopes.

C.  The most likely bond to break is C–C between carbons 2 and 3.

D.  The signal with the largest mass is due to the oxidation of the ketone in the spectrometer.

Naturally occurring gallium consists of the isotopes ⁷¹Ga and ⁶⁹Ga. What is the approximate percentage abundance of ⁶⁹Ga?

M_r(Ga) = 69.72.

A.  40 %

B.  50 %

C.  60 %

D.  75 %

Naturally occurring gallium consists of the isotopes ⁷¹Ga and ⁶⁹Ga. What is the approximate percentage abundance of ⁶⁹Ga?

M_r(Ga) = 69.72.

A.  40 %

B.  50 %

C.  60 %

D.  75 %

Naturally occurring gallium consists of the isotopes ⁷¹Ga and ⁶⁹Ga. What is the approximate percentage abundance of ⁶⁹Ga?

M_r(Ga) = 69.72.

A.  40 %

B.  50 %

C.  60 %

D.  75 %

Naturally occurring gallium consists of the isotopes ⁷¹Ga and ⁶⁹Ga. What is the approximate percentage abundance of ⁶⁹Ga?

M_r(Ga) = 69.72.

A.  40 %

B.  50 %

C.  60 %

D.  75 %