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

What is allotropy?

What do you understand by catenation?

Write a balanced equation for  BF₃ + LiH → ?

Draw the structure of BeCl₂ (vapour).

Draw the structure of BeCl₂ (solid).

Classify the following reaction in one of the reaction type studied in this unit.

\[\ce{CH3CH2Br + HS– → CH3CH2SH + Br–}\]

Classify the following reaction in one of the reaction type studied in this unit.

\[\ce{(CH3)2 C = CH2 + HCl → (CH3)2 ClC–CH3}\]

Classify the following reaction in one of the reaction type studied in this unit.

\[\ce{CH3CH2Br + HO– → CH2 = CH2 + H2O + Br–}\]

Classify the following reaction in one of the reaction type studied in this unit.

\[\ce{(CH3)3 C – CH2 OH + HBr → (CH3)2 CBrCH2CH3 + H2O}\]

What do you understand by the term “non-stoichiometric hydrides”? Do you expect this type of the hydrides to be formed by alkali metals? Justify your answer.

How do you expect the metallic hydrides to be useful for hydrogen storage? Explain.

Justify giving reactions that among halogens, fluorine is the best oxidant and among hydrohalic compounds, hydroiodic acid is the best reductant.

Which part of an atom was discovered by Rutherford's alpha particle scattering experiment?

Describe what is meant by significant figures.

Consider the compound, BCl₃. How will BCl₃ behave with water? Justify.

How many significant figures should be present in the answer of the following calculations?

`(2.5 xx 1.25 xx 3.5)/2.01`

Assertion (A): Significant figures for 0.200 is 3 where as for 200 it is 1.

Reason (R): Zero at the end or right of a number are significant provided they are not on the right side of the decimal point.

Which of the following conclusions could not be derived from Rutherford’s α -particle scattering experiment?

In the modern periodic table, elements are arranged in order of increasing atomic numbers which is related to the electronic configuration. Depending upon the type of orbitals receiving the last electron, the elements in the periodic table have been divided into four blocks, viz, s, p, d and f. The modern periodic table consists of 7 periods and 18 groups. Each period begins with the filling of a new energy shell. In accordance with the Arfbau principle, the seven periods have 2, 8, 8, 18, 18, 32 and 32 elements respectively. The seventh period is still incomplete. To avoid the periodic table being too long, the two series of f-block elements, called lanthanoids and actinoids are placed at the bottom of the main body of the periodic table.

The last element of the p-block in 6^th period is represented by the outermost electronic configuration.

Which of the following sequences contain atomic numbers of only representative elements?

(i) 3, 33, 53, 87

(ii) 2, 10, 22, 36

(iii) 7, 17, 25, 37, 48

(iv) 9, 35, 51, 88