English Medium इयत्ता ९ - CBSE Question Bank Solutions

The mass number of an element is 23 and it contains 11 electrons. What is the number of protons and neutrons in it? What is the atomic number of the element?

(a) What is meant by (i) atomic number, and (ii) mass number, of an element? Explain with the help of an example.

(b) What is the relation between the atomic number and mass number of an element?

(c) If an element M has mass number 24 and atomic number 12, how many neutrons does its atom contain?

The number of electrons in the atom of an element X is 15 and the number of neutrons is 16. Which of the following is the correct representation of an atom of this element ?

From the symbol `""_15^31"P"`, state :
(i) mass number of phosphorus,
(ii) atomic number of phosphorus, and
(iii) electron configuration of phosphorus.

From the symbol `""_15^31"P"`, state :  atomic number of phosphorus

The atom of an element X has 7 electrons in its M shell.
What is the atomic number of element X?

The atomic number of four elements A, B, C and D are 12, 13, 15 and 3 respectively. The element which cannot form a cation is :

Find the ratio by mass of the combining elements in the following compounds. (You may use Appendix-III)

CaCO₃

Find the ratio by mass of the combining elements in the following compounds. (You may use Appendix-III)

MgCl₂

Find the ratio by mass of the combining elements in the following compounds. (You may use Appendix-III)

H₂SO₄

Find the ratio by mass of the combining elements in the following compounds. (You may use Appendix-III)

C₂H₅OH

Find the ratio by mass of the combining elements in the following compounds. (You may use Appendix-III)

NH₃

Find the ratio by mass of the combining elements in the following compounds. (You may use Appendix-III)

Ca(OH)₂

Formula of sodium carbonate is ———— and that of ammonium sulphate is ————.

Which of the following are true for an element?

1. Atomic number = number of protons + number of electrons
2. Mass number = number of protons + number of neutrons
3. Atomic mass = number of protons = number of neutrons
4. Atomic number = number of protons = number of electrons

The ratio of the radii of hydrogen atom and its nucleus is ~ 10⁵. Assuming the atom and the nucleus to be spherical,

1. what will be the ratio of their sizes?
2. If atom is represented by planet earth ‘Re ’ = 6.4 ×106 m, estimate the size of the nucleus.

Show diagrammatically the electron distributions in a sodium atom and a sodium ion and also give their atomic number.

Which cell organelle plays a crucial role in detoxifying many poisons and drugs in a cell?

The cell organelle involved in forming complex sugars from simple sugars are

Silver nitrate solution is used to study