+91-8076753736[email protected]
logo
logo
-->

The Fundamental Unit Of Life

Question
CBSEENSC9005155
Wired Faculty App

What is phosphorescence?

Solution

Phosphorescence is luminescence that occurs when energy is supplied by electromagnetic radiation, such as ultraviolet light. The energy source excite an atom from a lower energy state into an excited higher energy state; then the electron releases the energy in the form of light when it falls back to a lower energy state. The light emission continues even after the radiation, responsible for producing phosphorescence is removed.

Some More Questions From The Fundamental Unit of Life Chapter

Summarize the rules for writing of distribution of electrons in various shells for the first eighteen elements.

Define valency by taking examples of silicon and oxygen.

Explain with examples, (i) Atomic number, (ii) Mass number, (iii) Isotopes, and (iv) Isobars. Give any two uses of isotopes also.

Na+ has completely filled K and L-shells. Explain.

If Z = 3, what would be the valency of the element? Also, name the element.

Composition of the nuclei of two atomic species X and Y are given as under


                              X        Y
Protons  =                6        6
Neutrons=                6        6

Give the mass numbers of X and Y. What is the relation between the two species?

For the following statements, write T for True and F for False.

(a) J.J. Thomson proposed that the nucleus of an atom contains only nucleons.

(b) A neutron is formed by an electron and a proton combining together. Therefore, it is neutral.

(c) The mass of an electron is about 1/2000 times that of proton.

(d) An isotope of iodine is used for making tincture iodine, which is used as a medicine.

Rutherford’s α-particle scattering experiment was responsible for the discovery of

Isotope of an element has

Mock Test Series

Mock Test Series

NCERT Sample Papers

Entrance Exams Preparation