(National Book Foundation - New Book/New Syllabus Based on National Curriculum Pakistan 2023-2024 and Onwards)
(National Book Foundation - New Book/New Syllabus Based on National Curriculum Pakistan 2023-2024 and Onwards)
(Class 8 General Science Notes for 8th Centralized Exam 2023-2024 and onward, FDE, Islamabad)
(Class 8 General Science Notes for 8th Centralized Exam 2023-2024 and onward, FDE, Islamabad)
Click Here for Solved MCQs Unit-5
D. Structured questions
1. Following figure shows some elements in the Periodic Table
a) Which elements are present in the same group?
Ans: A and F
b) Which elements are present in the same period?
Ans: A and C, B and D, F and E
c) What is the group number of C?
Ans: IV-A
d) Which elements have same number of electrons in their outermost shell?
Ans: A and F
e) Which element is a noble gas?
Ans: VIII-A
f) Which element is alkaline earth metal?
Ans: II-A
g) In which group element E is present? VA [
Ans: O Group or VIII Group
h) Which element has two electrons in its outermost shell?
Ans: B
2. Element carbon (At. No. 6) is present in Group IV-A in the periodic table.
a) Why is carbon placed in Group IV A in the periodic table?
Ans: Because carbon has four electrons in its outermost shell.
b) How many electrons carbon needs to complete its valence shell?
Ans: Four electrons
c) How many single bonds carbon can make?
Ans: Four single bonds carbon can make.
3. Draw electronic structures of:
a) Oxygen (At. No. 8)
O = 2, 6
Period = 2
Group = VI-A
b) Fluorine (At. No. 9)
O = 2, 7
Period = 2
Group = VII-A
c) Neon (At. No. 10)
O = 2, 8
Period = 2
Group = VIII-A
Write the difference in the electronic structure of these elements.
Ans: Oxygen, fluorine, and neon all belong to different groups on the periodic table, resulting in distinct electronic structures:
1. Oxygen (O): Atomic number 8. It has 8 electrons with 2 in the first energy level and 6 in the second energy level.
2. Fluorine (F): Atomic number 9. It has 9 electrons with 2 in the first energy level and 7 in the second energy level.
3. Neon (Ne): Atomic number 10. It has 10 electrons with 2 in the first energy level and 8 in the second energy level, making it a noble gas with a full outer electron shell.
E. Project work
1. Make an outline of the periodic table on a chart paper. Show the following elements on it some metals with brown colour, halogens with yellow colour, noble gases with red colour and some non-metals with blue colour.
2. Search and write the commercial uses of noble gases and alkali metals.
Ans: v
Noble gases, like helium and neon, are used in various commercial applications:
Helium: Used in balloons, airships, and as a coolant in nuclear reactors and MRI machines.
Neon: Used in neon signs, advertising displays, and as a component in high-voltage indicators.
Alkali metals, such as lithium and sodium, also have important commercial uses:
Lithium: Used in rechargeable lithium-ion batteries for electronic devices and electric vehicles, as well as in pharmaceuticals and ceramics.
Sodium: Used in the production of streetlights, fireworks, and certain types of glass, as well as in the chemical industry for various reactions and processes.
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