Science (English Medium) Class 12 - CBSE Question Bank Solutions

Assertion: \[\ce{HNO3}\] makes iron passive.

Reason: \[\ce{HNO3}\] forms a protective layer of ferric nitrate on the surface of iron.

On heating lead (II) nitrate gives a brown gas “A”. The gas “A” on cooling changes to colourless solid “B”. Solid “B” on heating with NO changes to a blue solid ‘C’. Identify ‘A’, ‘B’ and ‘C’ and also write reactions involved and draw the structures of ‘B’ and ‘C’.

Electronic configuration of a transition element X in +3 oxidation state is [Ar]3d⁵. What is its atomic number?

Metallic radii of some transition elements are given below. Which of these elements will have highest density?

Generally transition elements form coloured salts due to the presence of unpaired electrons. Which of the following compounds will be coloured in solid-state?

The magnetic nature of elements depends on the presence of unpaired electrons. Identify the configuration of transition element, which shows highest magnetic moment.

When \[\ce{KMnO4}\] solution is added to oxalic acid solution, the decolourisation is slow in the beginning but becomes instantaneous after some time because ______.

\[\ce{KMnO4}\] acts as an oxidising agent in acidic medium. The number of moles of \[\ce{KMnO4}\] that will be needed to react with one mole of sulphide ions in acidic solution is ______.

Interstitial compounds are formed when small atoms are trapped inside the crystal lattice of metals. Which of the following is not the characteristic property of interstitial compounds?

The magnetic moment is associated with its spin angular momentum and orbital angular momentum. Spin only magnetic moment value of \[\ce{Cr^{3+}}\] ion is ______.

Which of the following statements is not correct?

When acidified \[\ce{K2Cr2O7}\] solution is added to \[\ce{Sn^{2+}}\] salts then \[\ce{Sn^{2+}}\] changes to ______.

Highest oxidation state of manganese in fluoride is \[\ce{+4 (MnF4)}\] but highest oxidation state in oxides is \[\ce{+7 (Mn2O7)}\] because ______.

Although Zirconium belongs to 4d transition series and Hafnium to 5d transition series even then they show similar physical and chemical properties because ______.

Why is \[\ce{HCl}\] not used to make the medium acidic in oxidation reactions of \[\ce{KMnO4}\] in acidic medium?

Transition elements show magnetic moment due to spin and orbital motion of electrons. Which of the following metallic ions have almost same spin only magnetic moment?

(i) \[\ce{Co^{2+}}\]

(ii) \[\ce{Cr^{2+}}\]

(iii) \[\ce{Mn^{2+}}\]

(iv) \[\ce{Cr^{3+}}\]

Which of the following ions show higher spin only magnetic moment value?

(i) \[\ce{Ti^3+}\]

(ii) \[\ce{Mn2+}\]

(iii) \[\ce{Fe2+}\]

(iv) \[\ce{Co3+}\]

Transition elements form binary compounds with halogens. Which of the following elements will form \[\ce{MF3}\] type compounds?

(i) \[\ce{Cr}\]

(ii) \[\ce{Co}\]

(iii) \[\ce{Cu}\]

(iv) \[\ce{Ni}\]

Which of the following will not act as oxidising agents?

(i) \[\ce{CrO3}\]

(ii) \[\ce{MoO3}\]

(iii) \[\ce{WO3}\]

(iv) \[\ce{CrO^{2-}4}\]

Why does copper not replace hydrogen from acids?