Science (English Medium) Class 11 - CBSE Question Bank Solutions

Ions of an element of group 1 participate in the transmission of nerve signals and transport of sugars and aminoacids into cells. This element imparts yellow colour to the flame in flame test and forms an oxide and a peroxide with oxygen. Identify the element and write chemical reaction to show the formation of its peroxide. Why does the element impart colour to the flame?

The element which exists in liquid state for a wide range of temperature and can be used for measuring high temperature is ______.

Electronegativity of carbon atoms depends upon their state of hybridisation. In which of the following compounds, the carbon marked with asterisk is most electronegative?

Explain, how is the electronegativity of carbon atoms related to their state of hybridisation in an organic compound?

Assertion (A): All the carbon atoms in H₂C = C = CH₂ are sp² hybridised

Reason (R): In this molecule all the carbon atoms are attached to each other by double bonds.

The ring systems having following characteristics are aromatic.

(i) Planar ring containing conjugated π bonds.

(ii) Complete delocalisation of the π−electrons in ring system i.e. each atom in the ring has unhybridised p-orbital, and

(iii) Presence of (4n + 2) π−electrons in the ring where n is an integer (n = 0, 1, 2,...........) [Huckel rule].

Using this information classify the following compounds as aromatic/non-aromatic.

(A)	(B)	(C)	(D)
(E)	(F)	(G)

Which of the following compounds are aromatic according to Huckel’s rule?

(A)	(B)	(C)

(D)	(E)	(F)

Indicate the σ and π bonds in the following molecules:

HCONHCH₃

Indicate the σ and π bonds in the following molecules:

HCONHCH₃

Indicate the σ and π bonds in the following molecule:

\[\ce{HCONHCH3}\]

Indicate the σ and π bonds in the following molecules:

\[\ce{HCONHCH3}\]

Indicate the σ and π bonds in the following molecules:

\[\ce{HCONHCH3}\]

Indicate the σ and π bonds in the following molecule:

\[\ce{HCONHCH3}\]

Indicate the σ and π bonds in the following molecules:

\[\ce{HCONHCH3}\] 

Indicate the σ and π bonds in the following molecule:

\[\begin{array}{cc}
\ce{HCONHCH3}
\end{array}\]

Which important property did Mendeleev use to classify the elements in his periodic table and did he stick to that?

Calculate the total number of electrons present in one mole of methane.

What is the basic theme of the organisation in the periodic table?

Define octet rule.

For the process to occur under adiabatic conditions, the correct condition is ______.