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

Identify ‘C’ in the following:

Which one of the following reactions is not explained by the open chain Structure of glucose?

In the following reaction, identify A and B:

\[\begin{array}{cc}
\ce{C6H12O6 ->[Acetic anhydride] A}\\
\downarrow \text{Conc. nitric acid}\phantom{...}\\
\ce{B}\phantom{.................}\end{array}\]

Given below are two statements labelled as Assertion (A) and Reason (R).

Assertion (A): Alkyl halides are insoluble in water.

Reason (R): Alkyl halides have halogen attached to sp³ hybrid carbon.

Select the most appropriate answer from the options given below:

Given below are two statements labelled as Assertion (A) and Reason (R).

Assertion (A): SO₂ is reducing while TeO₂ is an oxidising agent.

Reason (R): Reducing property of dioxide decreases from SO₂ to TeO₂.

Select the most appropriate answer from the options given below:

Assertion: Total number of octahedral voids present in unit cell of cubic close packing including the one that is present at the body centre, is four.

Reason: Besides the body centre there is one octahedral void present at the centre of each of the six faces of the unit cell and each of which is shared between two adjacent unit cells.

Which of the following curves is in accordance with Freundlich adsorption isotherm?

Freundlich adsorption isotherm is given by the expression `x/m = kp^(1/n)` which of the following conclusions can be drawn from this expression.

(i) When `1/n` = 0, the adsorption is independent of pressure.

(ii) When `1/n` = 0, the adsorption is directly proportional to pressure.

(iii) When n = 0, `x/m` vs p graph is a line parallel to x-axis.

(iv) When n = 0, plot of `x/m` vs p is a curve.

Which of the following statements is correct about the role of substances added in the froth floation process?

(i) Collectors enhance the non-wettability of the mineral particles.

(ii) Collectors enhance the wettability of gangue particles.

(iii) By using depressants in the process two sulphide ores can be separated.

(iv) Froth stabilisers decrease wettability of gangue.

In the Froth Floatation process, zinc sulphide and lead sulphide can be separated by:

(i) using collectors.

(ii) adjusting the proportion of oil to water.

(iii) using depressant.

(iv) using froth stabilisers.

Which of the following ores are concentrated by froth floation?

(i) Haematite

(ii) Galena

(iii) Copper pyrites

(iv) Magnetite

How do we separate two sulphide ores by Froth Floatation Method? Explain with an example.

Match items of Column I with the items of Column II and assign the correct code:

Match items of Column I with the items of Column II and assign the correct code:

Assertion: Sulphide ores are concentrated by Froth Flotation method.

Reason: Cresols stabilise the froth in Froth Flotation method.

In a cyclotrimetaphosphoric acid molecule, how many single and double bonds are present?

Why is nitric oxide paramagnetic in gaseous state but the solid obtained on cooling it is diamagnetic?

In the ring test of \[\ce{NO^{-}3}\] ion, \[\ce{Fe^{2+}}\] ion reduces nitrate ion to nitric oxide, which combines with  \[\ce{Fe^{2+} (aq)}\] ion to form brown complex. Write the reactions involved in the formation of brown ring.

\[\ce{P4O6}\] reacts with water according to equation \[\ce{P4O6 + 6H2O -> 4H3PO3}\]. Calculate the volume of 0.1 M NaOH solution required to neutralise the acid formed by dissolving 1.1 g of \[\ce{P4O6}\] in \[\ce{H2O}\].

Nitric acid forms an oxide of nitrogen on reaction with P₄O₁₀. Write the reaction involved. Also write the resonating structures of the oxide of nitrogen formed.