Unit notes and practice questions
Everything here is for unit 1 of the Grade 9 Chemistry textbook: what the chapter covers, the short notes, practice questions with their answers, and the lesson video where one exists.
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A short video lesson on this chapter, made by Temari. It loads only when you press play.
The five branches of chemistry · 4 min · 2 past exam questions worked through
Tap a part to play the lesson from there.
The cards filed under this chapter on the Grade 9 Chemistry page. Open one at a time.
| Interdisciplinary Field | Overlapping Sciences |
|---|---|
| Biochemistry | Chemistry and Biology |
| Geochemistry | Chemistry and Geology |
| Physical chemistry | Chemistry and Physics |
| Medicinal chemistry | Chemistry and Medicine |
When you use it
Use when explaining how chemistry connects and overlaps with other fields of science.
Watch out
Chemistry is regarded as the central science because all physical and biological systems depend on matter.
Drafted from Grade 9 Chemistry, pages 2-18, then checked twice before it went up
| Branch | What it studies |
|---|---|
| Organic chemistry | Substances that contain carbon. Carbon forms a vast number of compounds, and most of the chemicals in living organisms are built on it. |
| Inorganic chemistry | Substances that are not primarily based on carbon, such as the compounds found in rocks and minerals. |
| Physical chemistry | Macroscopic properties, atomic properties and phenomena in chemical systems: reaction rates, the energy transferred in a reaction, and the structure of materials at the molecular level. |
| Analytical chemistry | The composition of matter. It separates, identifies and measures the chemicals in a sample. |
| Biochemistry | The chemical processes that take place in living things. |
When you use it
Chemistry is the study of the properties, composition and structure of substances, the changes they go through and the energy released or absorbed during those changes, and modern chemistry splits into five main disciplines. Reach for this table to name them, and remember that industrial chemistry and environmental chemistry sit inside chemistry's scope rather than among the five.
Watch out
Every compound that contains carbon looks organic, so students file carbon dioxide, carbon monoxide, sodium carbonate, sodium hydrogen carbonate, calcium carbide and potassium cyanide under organic chemistry. All six are studied as inorganic. Organic chemistry begins at the hydrocarbons, and five carbon families stay on the inorganic side: the oxides of carbon, the carbonates, the hydrogen carbonates, the cyanides and the carbides. So the true or false item 'organic chemistry is the study of chemicals that are not based on carbon' is false. Organic chemistry takes the ones that are based on carbon, and inorganic chemistry takes the rest.
10 multiple-choice questions written against this chapter, each with its answer and the reason. Try one before you open the answer.
Question 1
Which statement best defines chemistry?
Answer: B The science that deals with the properties, composition, and structure of substances, the transformations they undergo, and the energy released or absorbed during these processes.
Why
The unit defines chemistry as the science that deals with the properties, composition, and structure of substances, the transformations they undergo, and the energy that is released or absorbed. Studying living things is biology, and studying rocks and the earth is geology.
Question 2
Which branch of chemistry is the study of substances containing carbon?
Answer: D Organic chemistry
Why
Organic chemistry is the study of substances containing carbon. Inorganic chemistry studies substances that are, in general, not primarily based on carbon.
Question 3
According to the unit, geology is the study of what?
Answer: C Rocks and the earth
Why
The unit says that geology is the study of rocks and the earth. Matter and energy belong to physics, and chemical processes in living matter belong to biochemistry.
Question 4
Which group of drugs is used to kill microbes present in toilets, floors, and drains?
Answer: A Disinfectants
Why
The unit says disinfectants are used to kill the microbes present in toilets, floors, and drains. Analgesics relieve pain, anesthetics relieve pain during operations, and tranquilizers calm patients with mental diseases.
Question 5
Table 1.1 lists some large and medium scale chemical enterprises in Ethiopia. How many of the listed enterprises are in the region shown as A.A (Addis Ababa)?
Answer: D 6
Why
In Table 1.1, the enterprises in A.A are Chorra Gas and Chemical, Moha Soft Drinks CO2 Factory, Nefas Silk Paints, Kadisco Chemical Industry, Y.B Cosmetics, and Mekabe PLC (Cosmetics). That is 6 enterprises.
Question 6
The Grand Ethiopian Renaissance Dam (GERD) is located on the Blue Nile. According to the unit, how far upstream is it from the border with Sudan?
Answer: C 30 km
Why
The unit says the GERD is located about 30 km upstream of the border with Sudan. The number 6,450 is the power of the project in MW, not a distance.
Question 7
Which of the following is a chemical fertilizer named in the unit?
Answer: A Urea
Why
The unit lists calcium super phosphate, urea, ammonium sulphate, and sodium nitrate as chemical fertilizers. Penicillin, cisplatin, and Taxol are named in the medicine section, not as fertilizers.
Question 8
The unit says carbon is capable of forming a very large number of chemicals. How many chemicals does it say carbon can form so far?
Answer: C Over twenty million
Why
The organic chemistry section says carbon is capable of forming a tremendously vast number of chemicals, over twenty million so far.
Question 9
Which field of chemistry deals with the processes that control the abundance, composition, and distribution of chemical compounds and isotopes in geologic environments?
Answer: A Geochemistry
Why
The unit defines geochemistry as the overlap between chemistry and geology, and describes it as the study of the processes that control the abundance, composition, and distribution of chemical compounds and isotopes in geologic environments.
Question 10
The unit discusses the drug AZT, which is used for AIDS victims. Which statement about AZT is correct according to the unit?
Answer: B It fights the multiplication of the virus and prolongs the life of the victim.
Why
The unit says AZT does not cure HIV-AIDS. It fights the multiplication of the virus, which prolongs the life of the victim.
The app holds 12 questions on this unit, marked as you go. These are the first 10.
Unit 1 runs from page 1 to page 18 of the Ministry of Education edition.
Ministry of Education edition, English, 186 pages
Temari turns this chapter into timed practice and marks it as you go, with an AI tutor to explain anything that did not land.
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