Class 8
Subject Science (Notes )
National Book Foundation
Unit # 5
The Periodic Table of Elements
A. MCQS ( Choose the correct option)
1. Which of the following group contains alkali metals ?
a.IA b.IIA c.IIIA d.IVB
2. Which of the following elements is not an alkali metal ?
a.Li b. Na c.K d.Mg
3.An element has three electrons in its outermost shell. In which group of the Periodic Table it is likely to be found ?
a.Group IA b. Group IIA c. Group IIIA d.Group 0
4.Which of the following elements is a metalloid ?
a.Gold b.Sulphur c.Iron d.Silicon
5. Lithium is in the same group as
a.Magnesium b. Sodium c.Calcium d. Carbon
6. Which of the following is a halogen ?
a.Magnesium b.Sodium c.Helium d. Flourine
7.How many elements are present in the first period ?
a.2 b. 8 c. 18 d.32
8. How many electrons are present in the outermost shell in group IIIA elements ?
a. 1 b. 2 c.3 d.8
9.Which of the following group contains noble gases ?
a. IA b. IIA c. VIIA d. 0
10 . Period number of neon (atomic number 10 ) is
a. 1 b. 2 c. 3 d.4
B . Short Questions
1. Write common names for group of normal elements .
Answer .
Common names for groups of elements ;
Group IA - the alkali metals (except hydrogen )
Group IIA - the alkaline earth metals
Group VIIA - the halogens
Group 0 or VIIIA - the noble gases
2. Suggest why copper and aluminum are used in electricity cables .
Answer .
Because copper and aluminum are good conductors of electricity .
3. Many pots and pans are made of steel instead of pure iron . Why ?
Ans/- Because steel is a good thermal conductor.
4. Write three properties that make gold suitable for making jewelery .
Ans /- Gold is shiny , ductile and malleable metals .
5. In which portion of the periodic table are present.
a. Metals
b. Non-metals
6. Metals wires can be transformed into different shapes without breaking why ?
Ans/- Because metals are flexible.
7. Why electrical cables are covered with plastics ?
Ans /- Because plastic does not allow electric current to pass through it .
C. Long questions
Identify the location of following elements in the periodic table ?
a) Aluminum ( Atomic no . 13 )
Ans/-
b) Silicon ( Atomic no. 14)
c) Flourine ( Atomic no . 9 )
2. Justify that properties of metals make it suitable for making many objects or its parts . Explain with three examples .
Physical properties of metals make it suitable for making many objects or its parts.
Different metals are used for different purposes.
Most metals are not very hard or strong . We can make them harder and stronger . For this purpose metals are mixed with small amounts of other metals or non-metals ( such as carbon ) to form alloys. For example steel is an alloy of copper and zinc . Bronze is an alloy of copper and tin .
FAQ
Q. 1 What does group A and B elements called ?
Ans /- Group A elements are called main group elements and group B elements are called transition elements .
Q.2 Why does metals becomes flattens and thinners when you beat it ?
Ans /- Because metals are malleable.
Q.3 Is it metal flexible ?
Yes , metal is flexible and can be bend into different shapes without breaking it .