Advertisements
Advertisements
प्रश्न
Assertion (A): Cu cannot liberate hydrogen from acids.
Reason (R): Because it has positive electrode potential.
Assertion (A): Cu cannot liberate H2 on reaction with dilute mineral acids.
Reason (R): Cu has positive electrode potential.
विकल्प
Both assertion and reason are true, and reason is the correct explanation of the assertion.
Both assertion and reason are true but reason is not the correct explanation of assertion.
Assertion is not true but reason is true.
Both assertion and reason are false.
Advertisements
उत्तर
Both assertion and reason are true, and reason is the correct explanation of the assertion.
Explanation:
Copper has a positive electrode potential, so it is less reactive than hydrogen and cannot displace H+ ions from dilute acids to release hydrogen gas.
APPEARS IN
संबंधित प्रश्न
What are interstitial compounds?
Which of the following cations are coloured in aqueous solutions and why ?
Sc3+, V3+, Ti4+, Mn2+ (At. Nos. Sc = 21, V = 23, Ti = 22, Mn = 25)
Which of the 3d series of the transition metals exhibits the largest number of oxidation states and why?
Compare the stability of +2 oxidation state for the elements of the first transition series.
What are alloys?
Comment on the statement that elements of the first transition series possess many properties different from those of heavier transition elements.
Account for the following :
Ti4+ is colourless whereas V4+ is coloured in an aqueous solutions.
Two metallic elements A and B have the following standard oxidation potentials: A = 0·40v B = - 0·80v. What would you expect if element A was added to an aqueous salt solution of element B? Give a reason for your answer.
Read the passage given below and answer the following question:
The transition metals when exposed to oxygen at low and intermediate temperatures form thin, protective oxide films of up to some thousands of Angstroms in thickness. Transition metal oxides lie between the extremes of ionic and covalent binary compounds formed by elements from the left or right side of the periodic table. They range from metallic to semiconducting and deviate by both large and small degrees from stoichiometry. Since electron bonding levels are involved, the cations exist in various valence states and hence give rise to a large number of oxides. The crystal structures are often classified by considering a cubic or hexagonal close-packed lattice of one set of ions with the other set of ions filling the octahedral or tetrahedral interstices. The actual oxide structures, however, generally show departures from such regular arrays due in part to distortions caused by packing of ions of different size and to ligand field effects. These distortions depend not only on the number of d-electrons but also on the valence and the position of the transition metal in a period or group.
In the following questions, a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices on the basis of the above passage.
Assertion: Crystal structure of oxides of transition metals often show defects.
Reason: Ligand field effect cause distortions in crystal structures.
It has been observed that first ionization energy of 5 d series of transition elements are higher than that of 3d and 4d series, explain why?
The element with atomic number 53 belongs to
Photographic film and plates have - au essential ingredient of
Sodium this sulphate is used in photography because of its:-
Which of the following maxm magnetic moment?
Agcl is soluble in NH4OH. The solubility is due to the information of:-
Which of the following transition metals shows +1 and +2 oxidation states?
The given graph shows the trends in melting points of transition metals:
Explain the reason why Cr has the highest melting point and manganese (Mn) has a lower melting point.
Which of the following ions has the electronic configuration 3d6?
(Atomic number: Mn = 25, Co = 27, Ni = 28)
Write the number of unpaired electrons in Cr3+.
(Atomic number of Cr = 24)
The E° value for the Mn2+/Mn2+ couple is more positive than that of Cr3+/Cr2+ or Fe3+/Fe2+ due to the change of:
