Define one atomic mass unit (a.m.u.).

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An atomic mass unit is defined as 1/12^th the mass of a carbon-12 atom. It is a unit of mass that is used to represent the atomic masses of elements.

Elements are the simplest substances of matter that cannot be chemically reduced any further.
It is difficult to measure the mass of individual atoms as they are so small that the metric ‘grams’ is not practical to use.
The mass of one atom of C-12 is 1.99×10⁻²³g.
Atomic physicists and chemists, therefore, assumed the unified atomic mass unit (AMU) to describe the atomic masses on the basis of their subatomic particles.
The atomic mass unit is also expressed as a.m.u or u (unified).
A carbon-12 atom comprises 6 neutrons and 6 protons.
1 amu can be understood as the average of the proton and neutron rest mass.
We can represent 1 a.m.u. = 1.67377 x 10^-27 kilogram or 1.67377 x 10^-24gram.

Atomic Mass Unit

The unified atomic mass unit is a unit describing the mass of a neutral carbon-12 isotope at rest. Every proton and neutron weighs approximately 1 AMU.

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Difference Between Elements and Atoms	Atoms And Molecules	Laws of Chemical Combination
Writing Chemical Formulae	Mole Concept	Law of Conservation of Mass
Continuity Equation	Difference Between Atom and Ion	Molecular Weight Formula

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Consider the decomposition of hydrogen peroxide \( (\mathrm{H_2O_2}) \) as per the equation given below : \[ 2\mathrm{H_2O_2} \xrightarrow[\text{Alkaline medium}]{I^-} 2\mathrm{H_2O} + \mathrm{O_2} \] The mechanism for this reaction was found to be : Step I : \( \mathrm{H_2O_2} + I^- \longrightarrow \mathrm{H_2O} + IO^- \) (slow) Step II : \( \mathrm{H_2O_2} + IO^- \longrightarrow \mathrm{H_2O} + I^- + \mathrm{O_2} \) (fast) (a) Write the rate law expression. (b) Determine the order of reaction with respect to \( \mathrm{H_2O_2} \), \( I^- \) and overall order of reaction. (c) What is the molecularity of the reaction in Step II ?

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Conductivity of \( 2.5 \times 10^{-4} \) M methanoic acid solution is \( 5.25 \times 10^{-5} \) S cm\(^{-1}\).
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[Given : \( \lambda^{\circ}_{(\mathrm{H^+})} = 349.5 \) S cm\(^2\) mol\(^{-1}\) and \( \lambda^{\circ}_{(\mathrm{HCOO^-})} = 50.5 \) S cm\(^2\) mol\(^{-1}\)]

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From the given data of \(E^{\circ}\) values, answer the following questions :
(I) Why \(E^{\circ}_{M^{2+}/M}\) show irregular trend in the above values ?
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(III) Why \(E^{\circ}_{Mn^{2+}/Mn}\) value is highly negative ?

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Write the name of basic building units of proteins and nucleic acids. How can you differentiate between Fibrous and Globular proteins on the basis of their structures ?

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(a) Write two structural differences between DNA and RNA.
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An organic compound (X) has the molecular formula \(C_5H_{10}O\). Draw structures for (X) if it:
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(II) does not give Tollen's test and iodoform test but undergoes Aldol condensation.
(III) undergoes Cannizzaro's reaction.

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Define one atomic mass unit (a.m.u.).

CBSE CLASS XII Related Questions

3.
From the given data of \(E^{\circ}\) values, answer the following questions :
(I) Why \(E^{\circ}_{M^{2+}/M}\) show irregular trend in the above values ?
(II) Why is \(E^{\circ}_{Cu^{2+}/Cu}\) value exceptionally positive ?
(III) Why \(E^{\circ}_{Mn^{2+}/Mn}\) value is highly negative ?

4.
Write the name of basic building units of proteins and nucleic acids. How can you differentiate between Fibrous and Globular proteins on the basis of their structures ?

5.
(a) Write two structural differences between DNA and RNA.
(b) Which component of starch is a branched chain polymer of \( \alpha \)-D-(+)-glucose ? Write its one characteristic feature.
(c) Which types of bonds hold the polypeptide chains in fibrous proteins ?

6.
An organic compound (X) has the molecular formula \(C_5H_{10}O\). Draw structures for (X) if it:
(I) does not give Tollen's test but gives a positive iodoform test.
(II) does not give Tollen's test and iodoform test but undergoes Aldol condensation.
(III) undergoes Cannizzaro's reaction.

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Define one atomic mass unit (a.m.u.).

CBSE CLASS XII Related Questions

3.From the given data of \(E^{\circ}\) values, answer the following questions : (I) Why \(E^{\circ}_{M^{2+}/M}\) show irregular trend in the above values ? (II) Why is \(E^{\circ}_{Cu^{2+}/Cu}\) value exceptionally positive ? (III) Why \(E^{\circ}_{Mn^{2+}/Mn}\) value is highly negative ?

4.Write the name of basic building units of proteins and nucleic acids. How can you differentiate between Fibrous and Globular proteins on the basis of their structures ?

5.(a) Write two structural differences between DNA and RNA.(b) Which component of starch is a branched chain polymer of \( \alpha \)-D-(+)-glucose ? Write its one characteristic feature.(c) Which types of bonds hold the polypeptide chains in fibrous proteins ?

6.An organic compound (X) has the molecular formula \(C_5H_{10}O\). Draw structures for (X) if it: (I) does not give Tollen's test but gives a positive iodoform test. (II) does not give Tollen's test and iodoform test but undergoes Aldol condensation. (III) undergoes Cannizzaro's reaction.

Comments

SUBSCRIBE TO OUR NEWS LETTER

3.
From the given data of \(E^{\circ}\) values, answer the following questions :
(I) Why \(E^{\circ}_{M^{2+}/M}\) show irregular trend in the above values ?
(II) Why is \(E^{\circ}_{Cu^{2+}/Cu}\) value exceptionally positive ?
(III) Why \(E^{\circ}_{Mn^{2+}/Mn}\) value is highly negative ?

4.
Write the name of basic building units of proteins and nucleic acids. How can you differentiate between Fibrous and Globular proteins on the basis of their structures ?

5.
(a) Write two structural differences between DNA and RNA.
(b) Which component of starch is a branched chain polymer of \( \alpha \)-D-(+)-glucose ? Write its one characteristic feature.
(c) Which types of bonds hold the polypeptide chains in fibrous proteins ?

6.
An organic compound (X) has the molecular formula \(C_5H_{10}O\). Draw structures for (X) if it:
(I) does not give Tollen's test but gives a positive iodoform test.
(II) does not give Tollen's test and iodoform test but undergoes Aldol condensation.
(III) undergoes Cannizzaro's reaction.