Ncert Solutions Chemistry Class 11th

An ideal body, which emits and absorbs radiations of all frequencies uniformly, is called a black body and the radiation emitted by such a body is called black body radiation. In practice, no such body exists. Carbon black approximates fairly closely to black body. A good physical approximation to a black body is a cavity with a tiny hole, which has no other opening. Any ray entering the hole will be reflected by the cavity walls and will be eventually absorbed by the walls.

Werner Heisenberg a German physicist in 1927, stated uncertainty principle which is the consequence of dual behaviour of matter and. It states that it is impossible to determine simultaneously, the exact position and exact momentum (or velocity) of an electron.

It rules out existence of definite paths or trajectories of electrons and other similar particles.

This is a multiple choice answer as classified in NCERT Exemplar

(ii) R–Cl< RBr < RI 

The reduction of alkyl halides depends upon the C-X bond strength i.e. lesser the bond strength higher will be the reactivity of alkyl halide. As down the group size of the halogens increases thus the bond strength decreases.

The chemical properties of an atom are controlled by the number of electrons in the atom, which remains the same despite the change or variation in atomic masses in case the of isotopes.

Kindly go through the solution

(d) 2l + 1

This is a multiple choice answer as classified in NCERT Exemplar

(i) I₂< Br₂< Cl₂< F₂

The reactivity of halogens with alkanes depends on the electronegativity i.e. higher the electronegativity higher would be the reaction. As down the group reactivity decrease so thus its reactivity.

Kindly go through the solution

(a) ionisation energy

Kindly go through the solution

(d) 6.62 x 10^-34 Js

This is a multiple choice answer as classified in NCERT Exemplar

(iv) C > B > D > A

The boiling point increases with the increase in the length of the side chain. However, with the branching, the boiling point decreases due to the decrease in the surface area.

Kindly go through the solution

(c) H