General Science
7th Class
Chapter 6
Chemical Bonds
Questions
6.1 Encircle the correct option.
1. A molecule consists of two or more
a. compounds b. atoms c. formulae d. elements
2. Which of the following is a cation?
a. H2 b. H2O c. CO2 d. NH+4
3. Which of the following is an anion?
a. F b. Cl c. S2- d. NH3
4. Oxygen is a:
a. monovalent element b. divalent element
c. trivalent element d. tetravalent element
5. Chemical bond between N2 molecule is:
a. ionic b. single covalent c. double covalent d. triple covalent
6. How many atoms from one molecule of chlorine gas?
a. 1 b. 2 c. 3 d. 4
7. Outermost shell of sodium atom has _________ electron (s):
a. 1 b. 2 c. 3 d. 4
8. Outermost shell of chlorine atom has ________ electron(s):
a. 1 b. 2 c. 6 d. 7
9. Which of the following has stable electronic configuration?
a. H b. He c. C d. Li
10. Which of the following has double covalent bond?
a. Br2 b. CO2 c. HCl d. N2
6.2 Define the following and explain with examples:
1. Valency
2. Ion
3. Formula
4. Bond
5. Electronic configuration
1. Valency
Ans.
The combining capacity of atoms with other atoms is called valency.
Example: Valency of oxygen is 2 as it combines with two hydrogen atoms to from H2O
2. Ion
Ans.
The charged particles (atom or group of atoms) are called ion.
Example: Na+ is an atom having charge on it while HSO4- is a group of atoms having charge on it, both Na+ and HSO4- are ions.
3. Formula
Ans.
A symbolic representation of an element or compound is called formula.
Example: Formula of oxygen is O2and sulphuric acid is H2SO4
.
4. Bond
Ans.
The force of attraction that holds stoms to together in a substance is called bond.
Example: Bond is present in NaCl which bond Na+ and Cl- together.
5. Electronic configuration
Ans.
The distribution of electrons in the shells around nucleus of an atom is called electronic configuration.
Example: Electronic configuration of Lithium (Li) is 1s2 2s1.
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