Solutions of Metals and Non-metals (Page No - 171) - Chemistry Lakhmir Singh, Class 10 | Extra Documents, Videos & Tests for Class 10 PDF Download

Question 67:
Two non-metals combine with each other by the sharing of electrons to form a compound X.
(a) What type of chemical bond is present in X ?
(b) State whether X will have a high melting point or low melting point.
(c) Will it be a good conductor of electricity or not ?
(d) Will it dissolve in an organic solvent or not ?
Solution :
(a) Covalent bond
(b) Low melting point
(c) No
(d) Yes

Question 68:
A metal combines with a non-metal by the transfer of electrons to form a compound Y.
(i) State the type of bonds in Y.
(ii) What can you say about its melting point and boiling point ?
(iii) Will it be a good conductor of electricity ?
(iv) Will it dissolve in an organic solvent or not ?
Solution :
(i) Ionic bond
(ii) High melting point and boiling point
(iii) Yes
(iv) No

Question 69:
The electronic configurations of three elements X, Y and Z are as follows :
X     2, 4
Y     2,1
Z     2, 1
(a) Which two elements will combine to form an ionic compound ?
(b) Which two elements will react to form a covalent compound ?
Give reasons for your choice.
Solution :
(a) Y and Z will form an ionic compound because an ionic bond is formed when one of the atoms can donate electrons to achieve the inert gas configuration, and the other atom needs electrons to achieve the inert gas configuration. Since Y has 7 and Z has 1 electron in their outermost shell, they would form an ionic bond.
(b) X and Y will react to form a covalent compound because a covalent bond is formed when both the reacting atoms need electrons to achieve the inert gas electron arrangement.

Question 70:
An element A has 4 valence electrons in its atom whereas element B has only one valence electron in its atom. The compound formed by A and B does not conduct electricity. What is the nature of chemical bond in the compound formed ? Give its electron-dot structure.
Solution :
Covalent bond will be formed since covalent compounds are non conductors of electricity.

Question 71:
In the formation of a compound XY₂ atom X gives one electron to each Y atom. What is the nature of bond in XY₂ ? Give two properties of XY₂.
Solution :
XY₂ has ionic bonds.
(i) XY₂ would conduct electricity when dissolved in water.
(ii) XY₂ would have high melting and boiling point.

Question 72:
An element ‘A’ has two electrons in the outermost shell of its atom and combines with an element ‘B’ having seven electrons in the outermost shell, forming the compound AB2. The compound when dissolved in water conducts electric current. Giving reasons, state the nature of chemical bond in the compound.
Solution :
AB₂ forms ionic bonds because an aqueous solution of an ionic compound conducts electricity because there are plenty of free ions in the solution which are able to conduct electric current.

Question 73:
The electronic configurations of two elements A and B are given below :
A    2, 6
B    2, 8, 1
(a) What type of chemical bond is formed between the two atoms of A ?
(b) What type of chemical bond will be formed between the atoms of A and B ?
Solution :
(a) Covalent bond.
(b) Ionic bond .

Question 74:
Four elements A, B, C and D have the following electron arrangements in their atoms :
A    2, 8, 6
B    2, 8, 8
C    2, 8, 8, 1
D    2,1
(a) What type of bond is formed when element C combines with element D ?
(b) Which element is an inert gas ?
(c) What will be the formula of the compound between A and C ?
Solution :
(a) Ionic bond will be formed; element C donates its electron to element D.
(b) B is an inert gas; has complete octet configuration.
(c) C₂ A; element A needs two electrons to complete its octet.

Question 75:
An element X of atomic number 12 combines with an element Y of atomic number 17 to form a compound XY₂. State the nature of chemical bond in XY₂ and show how the electron configurations of X and Y change in the formation of this compound.
Solution :
XY₂ forms ionic bo nd. The electronic configuration of X changes from 2, 8, 2 to 2, 8, it donates its 2 electrons to two Y atoms. Hence, the elec tronic configuration of Y changes f rom 2, 8, 7 to 2, 8, 8 giving the compound XY2.

Question 76:
The electronic configurations of three elements A, B and C are as follows :
A    2, 8, 1
B    2, 8, 7
C    2, 4
(a) Which of these elements is a metal ?
(b) Which of these elements are non-metals ?
(c) Which two elements will combine to form an ionic bond ?
(d) Which two elements will combine to form a covalent bond ?
(e) Which element will form an anion of valency 1 ?
Solution :
(a) A is a metal
(b) B and C are non-metals
(c) A and B combines to form an ionic bond.
(d) B and C combines to form a covalent bond.
(e) B will form an anion with valency 1 since it needs only 1 electron to complete its octet.

Question 77:
The electronic configurations of four particles A, B, C and D are given below :
A    2, 8, 8
B    2, 8, 2
C    2, 6
D    2, 8
Which electronic configuration represents :
(i) magnesium atom ? (ii) oxygen atom ?
(iii) sodium ion ? (iv) chloride ion ?
Solution :
(i) B: Magnesium atom (At. no. = 12)
(ii) C: Oxygen atom (At. no. = 8)
(iii) D: Sodium ion (E.C = 2, 8)
(iv) A: Chloride ion (E.C = 2, 8, 8)