📚 Chapter 1: Essential Ideas in Chemistry - 50 Practice Questions

🧪 PART 1: CHEMISTRY IN CONTEXT & SCIENTIFIC METHOD

Question 1

Why is chemistry often called "the central science"?

A) Because it was discovered in Central Europe

B) Because it connects and overlaps with many other scientific disciplines

C) Because it only studies central atoms in molecules

D) Because it is the oldest science

Correct Answer: B

Explanation (English): Chemistry is called the central science because it serves as a bridge connecting physics, biology, medicine, environmental science, astronomy, and many other fields. It provides the fundamental understanding of matter that underlies all other sciences. For example, biology studies living organisms whose processes are chemical reactions, and physics provides the laws that govern these chemical interactions.

ማብራሪያ (Amharic): ኬሚስትሪ "ማዕከላዊ ሳይንስ" የሚባለው ከሌሎች የሳይንስ ዘርፎች ጋር ያለውን ግንኙነት በማሳየቱ ነው። እንደ ፊዚክስ፣ ባዮሎጂ፣ ሕክምና እና የአካባቢ ጥናት ያሉ የተለያዩ ዘርፎችን ያገናኛል። ለምሳሌ ባዮሎጂ ሕይወት ያላቸውን ነገሮች ያጠናል፣ እነዚህ ሂደቶች ግን ኬሚካላዊ ምላሾች (chemical reactions) ናቸው።

Question 2

Which sequence correctly represents the scientific method process?

A) Theory → Experiment → Hypothesis → Law

B) Observation → Hypothesis → Experiment → Conclusion → Theory/Law

C) Experiment → Observation → Law → Theory

D) Hypothesis → Law → Experiment → Conclusion

Correct Answer: B

Explanation (English): The scientific method typically follows this logical sequence: First, you make an observation and ask a question. Then you propose a hypothesis (a tentative explanation). Next, you perform experiments to test your hypothesis. After analyzing the results, you draw a conclusion. If the hypothesis is repeatedly supported, it may develop into a theory (a well-tested explanation) or a law (a description of a consistent natural phenomenon).

ማብራሪያ (Amharic): ሳይንሳዊ ዘዴ የሚከተለው ቅደም ተከተል ነው፦ መጀመሪያ መመልከት (observation) ይደረጋል፣ ከዚያ መላምት (hypothesis) ይቀርባል፣ ቀጥሎ ሙከራ (experiment) ይካሄዳል፣ ከዚያም መደምደሚያ (conclusion) ላይ ይደረሳል፣ በመጨረሻም ወደ ንድፈ ሃሳብ (theory) ወይም ህግ (law) ሊለወጥ ይችላል።

Question 3

A scientist observes that plants grow taller when given a new fertilizer. She proposes that "the fertilizer promotes plant growth." This statement is an example of a:

A) Scientific law

B) Theory

C) Hypothesis

D) Experiment

Correct Answer: C

Explanation (English): This is a hypothesis because it's a tentative explanation that can be tested through experimentation. It's not a theory (which would be well-established after many tests) or a law (which describes a consistent natural phenomenon). The statement is a proposed explanation that needs to be verified through controlled experiments.

ማብራሪያ (Amharic): ይህ መላምት (hypothesis) ነው። ምክንያቱም ጊዜያዊ ማብራሪያ ሲሆን በሙከራ መረጋገጥ ይጠበቅበታል። ንድፈ ሃሳብ (theory) ወይም ህግ (law) አይደለም፤ ምክንያቱም እነዚህ ብዙ ጊዜ ከተሞከሩ እና ከተረጋገጡ በኋላ ይመጣሉ።

Question 4

Which of the following statements best describes a scientific law?

A) An educated guess that needs testing

B) A well-tested explanation for a wide range of phenomena

C) A concise statement that describes a consistent natural phenomenon

D) A tentative explanation based on limited observations

Correct Answer: C

Explanation (English): A scientific law is a concise statement, often mathematical, that describes a consistent relationship or pattern observed in nature. It tells us what happens, but not necessarily why. For example, the law of conservation of matter states that matter cannot be created or destroyed in chemical reactions. Unlike a theory (which explains why), a law simply describes what always happens under certain conditions.

ማብራሪያ (Amharic): ሳይንሳዊ ህግ (law) በተፈጥሮ ውስጥ ያለማቋረጥ የሚስተዋለውን ክስተት በአጭር መልኩ የሚገልጽ ነው። "ምን እንደሚሆን" ይነግረናል እንጂ "ለምን እንደሚሆን" አይገልጽም። ለምሳሌ የማትሪያ ጥበቃ ህግ (law of conservation of matter) ማትሪያ አይፈጠርም አይጠፋም ይላል።

Question 5

A student looks at an iceberg and thinks about individual water molecules. The iceberg represents which domain of chemistry, and the water molecules represent which domain?

A) Iceberg: Microscopic; Water molecules: Macroscopic

B) Iceberg: Macroscopic; Water molecules: Microscopic

C) Iceberg: Symbolic; Water molecules: Macroscopic

D) Iceberg: Microscopic; Water molecules: Symbolic

Correct Answer: B

Explanation (English): The macroscopic domain deals with things we can see, touch, and measure directly, like an iceberg. The microscopic domain deals with atoms and molecules, which are too small to see with the naked eye and must be imagined, like individual water molecules (H₂O). The symbolic domain would be representing them with symbols like "H₂O" or chemical equations.

ማብራሪያ (Amharic): ማክሮስኮፒክ ጎራ (macroscopic domain) በአይን የምናያቸውን እንደ በረዶ ያሉ ትላልቅ ነገሮችን ያጠናል። ማይክሮስኮፒክ ጎራ (microscopic domain) ደግሞ እንደ ውሃ ሞለኪውሎች ያሉ በአይን የማይታዩ ትናንሽ ቅንጣቶችን ያጠናል።

Question 6

The chemical formula H₂O is an example of which domain of chemistry?

A) Macroscopic domain

B) Microscopic domain

C) Symbolic domain

D) Physical domain

Correct Answer: C

Explanation (English): The formula H₂O belongs to the symbolic domain, which is the specialized language chemists use to represent components of the macroscopic and microscopic domains. It's a symbol that represents both a single water molecule (microscopic) and a collection of water (macroscopic). This domain also includes chemical equations, graphs, and mathematical calculations.

ማብራሪያ (Amharic): H₂O የሚለው ቀመር ምሳሌያዊ ጎራ (symbolic domain) ነው። ይህ ጎራ ኬሚስቶች ማትሪያን ለመግለጽ የሚጠቀሙበት ልዩ ቋንቋ ነው። እንደ ኬሚካላዊ ቀመሮች፣ ስሌቶች እና ግራፎች ያሉ ነገሮችን ያካትታል።

🧊 PART 2: STATES AND CLASSIFICATION OF MATTER

Question 7

Which of the following correctly lists the three common states of matter on Earth?

A) Solid, liquid, plasma

B) Solid, liquid, gas

C) Liquid, gas, plasma

D) Solid, gas, plasma

Correct Answer: B

Explanation (English): The three most common states of matter found on Earth are solid, liquid, and gas. Plasma is a fourth state of matter found in stars and lightning, but it's not common on Earth's surface. Solids have definite shape and volume, liquids have definite volume but take the shape of their container, and gases have neither definite shape nor volume.

ማብራሪያ (Amharic): በምድር ላይ በብዛት የሚገኙት የማትሪያ ሁኔታዎች ጠንካራ (solid) ፣ ፈሳሽ (liquid) እና ጋዝ (gas) ናቸው። ፕላዝማ (plasma) አራተኛው ሁኔታ ሲሆን በከዋክብት እና በመብረቅ ውስጥ ይገኛል።

Question 8

What is the key difference between mass and weight?

A) Mass is measured in kilograms, weight in grams

B) Mass is the amount of matter, weight is the force of gravity on that matter

C) Mass changes with location, weight remains constant

D) There is no difference; they are the same thing

Correct Answer: B

Explanation (English): Mass is a measure of the amount of matter in an object and remains constant regardless of location. Weight is the force that gravity exerts on that mass and changes with gravitational field strength. An astronaut's mass is the same on Earth and the moon, but their weight on the moon is only one-sixth of their Earth weight because the moon's gravity is weaker.

ማብራሪያ (Amharic): ክብደት (mass) ማለት በአንድ ነገር ውስጥ ያለ የማትሪያ መጠን ሲሆን ቦታው ሳይለወጥ ይቆያል። ክብደት (weight) ማለት ስበት በዚያ ክብደት ላይ የሚፈጥረው ኃይል ሲሆን እንደ ቦታው ይለወጣል። ጨረቃ ላይ ያለ ጠፈርተኛ ክብደቱ (mass) አይለወጥም ነገር ግን ክብደቱ (weight) ይቀንሳል።

Question 9

The law of conservation of matter states that:

A) Matter can be created but not destroyed

B) Matter can be destroyed but not created

C) There is no detectable change in the total quantity of matter during a chemical or physical change

D) Matter changes form but always increases in total amount

Correct Answer: C

Explanation (English): The law of conservation of matter states that in any chemical reaction or physical change, matter is neither created nor destroyed. The total mass of substances before a reaction equals the total mass after the reaction, even though the substances may change form. For example, when wood burns, the mass of the wood plus oxygen equals the mass of the ash, smoke, and gases produced.

ማብራሪያ (Amharic): የማትሪያ ጥበቃ ህግ (law of conservation of matter) እንደሚለው በማንኛውም ኬሚካላዊ ወይም አካላዊ ለውጥ ወቅት ማትሪያ አይፈጠርም አይጠፋም። የምላሹ ቅድመ-ሁኔታ ክብደት ከድህረ-ሁኔታ ክብደት ጋር እኩል ነው።

Question 10

A pure substance that cannot be broken down into simpler substances by chemical changes is called:

A) A compound

B) A mixture

C) An element

D) A solution

Correct Answer: C

Explanation (English): An element is the simplest form of matter that cannot be broken down into simpler substances by ordinary chemical means. Examples include iron (Fe), oxygen (O), and gold (Au). In contrast, compounds (like water, H₂O) can be broken down into elements, and mixtures are physical combinations of substances.

ማብራሪያ (Amharic): ንጥረ ነገር (element) በኬሚካላዊ ምላሽ ወደ ቀላል ንጥረ ነገር መከፋፈል የማይችል ንጹህ ንጥረ ነገር ነው። ለምሳሌ ብረት (Fe)፣ ወርቅ (Au) እና ኦክስጅን (O)። ውህዶች (compounds) ግን ወደ ንጥረ ነገሮች መከፋፈል ይችላሉ።

Question 11

Which of the following is an example of a compound?

A) Oxygen gas (O₂)

B) Gold (Au)

C) Table salt (NaCl)

D) Copper wire (Cu)

Correct Answer: C

Explanation (English): Table salt (NaCl) is a compound because it consists of two different elements (sodium and chlorine) chemically bonded together in a fixed ratio. Oxygen gas (O₂) is a molecule of an element (same type of atoms). Gold (Au) and copper (Cu) are pure elements (only one type of atom).

ማብራሪያ (Amharic): ጨው (NaCl) ውህድ (compound) ነው ምክንያቱም ሁለት የተለያዩ ንጥረ ነገሮች (ሶዲየም እና ክሎሪን) በኬሚካል ተያይዘው የተሰሩ ናቸው። ኦክስጅን ጋዝ (O₂) የንጥረ ነገር ሞለኪውል ነው (ተመሳሳይ አቶሞች)። ወርቅ (Au) እና መዳብ (Cu) ንጹህ ንጥረ ነገሮች ናቸው።

Question 12

Italian salad dressing with oil, vinegar, and herbs separating into layers is an example of:

A) A homogeneous mixture

B) A heterogeneous mixture

C) A pure substance

D) A compound

Correct Answer: B

Explanation (English): Italian dressing is a heterogeneous mixture because its composition is not uniform throughout. You can see the different components (oil, vinegar, herbs) separating into distinct layers or regions. The composition varies from one point to another within the mixture. In contrast, a homogeneous mixture (solution) would look the same throughout.

ማብራሪያ (Amharic): የጣሊያን ሰላጣ ማጣፈጫ የተለያየ አይነት ድብልቅ (heterogeneous mixture) ነው ምክንያቱም ውህደቱ በሁሉም ቦታ ተመሳሳይ አይደለም። ዘይቱን፣ ኮምጣጤውን እና ቅጠላ ቅጠሎቹን በተናጠል ማየት ይቻላል።

Question 13

Which of the following is a homogeneous mixture?

A) Sand and water

B) Oil and water

C) Salt dissolved in water

D) A bowl of cereal with milk

Correct Answer: C

Explanation (English): Salt dissolved in water is a homogeneous mixture (also called a solution) because the salt particles are evenly distributed throughout the water, and you cannot see the individual components. It appears uniform throughout. The other options are heterogeneous mixtures where you can see distinct components or layers.

ማብራሪያ (Amharic): ጨው በውሃ ውስጥ መሟሟት አንድ አይነት ድብልቅ (homogeneous mixture) ወይም መፍትሄ (solution) ነው። ምክንያቱም የጨው ቅንጣቶች በውሃ ውስጥ በእኩል መጠን ተሰራጭተዋል እና ክፍሎቹን በዓይን ማየት አይቻልም።

Question 14

What is the difference between a compound and a mixture?

A) Compounds are physically combined; mixtures are chemically combined

B) Compounds have fixed composition; mixtures have variable composition

C) Compounds can be separated by physical means; mixtures cannot

D) There is no difference

Correct Answer: B

Explanation (English): The key difference is that compounds have a fixed, definite composition by mass (e.g., water always has 11.2% hydrogen and 88.8% oxygen). Mixtures can have variable composition (you can make a salt solution with more or less salt). Compounds are chemically combined and require chemical reactions to separate, while mixtures are physically combined and can be separated by physical means.

ማብራሪያ (Amharic): ዋናው ልዩነት ውህዶች (compounds) ቋሚ ውህደት አላቸው (ለምሳሌ ውሃ ሁልጊዜ 11.2% ሃይድሮጅን እና 88.8% ኦክስጅን አለው)። ድብልቆች (mixtures) ደግሞ ተለዋዋጭ ውህደት አላቸው (ብዙም ወይም ትንሽ ጨው መጨመር ይቻላል)።

Question 15

Which two elements make up about 75% of the Earth's crust?

A) Iron and aluminum

B) Oxygen and silicon

C) Carbon and hydrogen

D) Calcium and sodium

Correct Answer: B

Explanation (English): According to Table 1.1 in the module, oxygen (O) constitutes about 49.20% and silicon (Si) about 25.67% of the Earth's crust, together making up approximately 75% of the total. The remaining elements, including aluminum, iron, calcium, and others, make up the other 25%.

ማብራሪያ (Amharic): በምእራፉ ሠንጠረዥ 1.1 መሠረት ኦክስጅን (O) 49.20% እና ሲሊከን (Si) 25.67% የምድርን ቅርፊት ይሸፍናሉ። እነዚህ ሁለት ንጥረ ነገሮች አንድ ላይ 75% ያህሉን ይይዛሉ።

🔥 PART 3: PHYSICAL AND CHEMICAL PROPERTIES

Question 16

Which of the following is a physical property?

A) Flammability

B) Reactivity with acid

C) Density

D) Toxicity

Correct Answer: C

Explanation (English): Density is a physical property because it can be measured or observed without changing the chemical composition of the substance. Flammability, reactivity with acid, and toxicity are chemical properties because they describe how a substance can change into a new substance (burning, reacting, causing harm through chemical reactions).

ማብራሪያ (Amharic): ጥግግት (density) አካላዊ ባህሪ (physical property) ነው ምክንያቱም የኬሚካላዊ ውህደቱን ሳይቀይሩ መለካት ይቻላል። ተቀጣጣይነት (flammability)፣ ከአሲድ ጋር ምላሽ መስጠት እና መርዛማነት ኬሚካላዊ ባህሪያት ናቸው።

Question 17

Which of the following describes a chemical change?

A) Ice melting into water

B) Sugar dissolving in coffee

C) An iron nail rusting

D) Wax melting from a candle

Correct Answer: C

Explanation (English): Rusting of iron is a chemical change because the iron reacts with oxygen to form a new substance (iron oxide/rust) with different properties. The original iron is transformed into something else. Melting ice, dissolving sugar, and melting wax are physical changes - the substances change form or state but remain chemically the same (water is still H₂O, sugar is still sugar, wax is still wax).

ማብራሪያ (Amharic): ብረት ዝገት መያዝ ኬሚካላዊ ለውጥ (chemical change) ነው ምክንያቱም ብረቱ ከኦክስጅን ጋር ተደምሮ አዲስ ንጥረ ነገር (ዝገት) ይፈጥራል። በረዶ መቅለጥ፣ ስኳር መሟሟት እና ሰም መቅለጥ አካላዊ ለውጦች (physical changes) ናቸው።

Question 18

Which of the following is a chemical property of sodium?

A) It is a soft, silvery-white metal

B) It has a melting point of 97.7°C

C) It reacts violently with water

D) It conducts electricity well

Correct Answer: C

Explanation (English): The fact that sodium reacts violently with water is a chemical property because it describes how sodium undergoes a chemical change to form new substances (sodium hydroxide and hydrogen gas). Its softness, color, melting point, and electrical conductivity are all physical properties that can be observed without changing its chemical identity.

ማብራሪያ (Amharic): ሶዲየም ከውሃ ጋር ኃይለኛ ምላሽ መስጠቱ ኬሚካላዊ ባህሪ (chemical property) ነው ምክንያቱም ሶዲየም እንዴት ኬሚካላዊ ለውጥ እንደሚያመጣ ይገልጻል። ለስላሳነቱ፣ ቀለሙ፣ የማቅለጫ ነጥቡ እና ኤሌክትሪክ ማስተላለፍ ችሎታው አካላዊ ባህሪያት ናቸው።

Question 19

When water boils and turns into steam, this is an example of:

A) A chemical change

B) A physical change

C) A chemical property

D) A new compound being formed

Correct Answer: B

Explanation (English): Boiling water is a physical change because the water molecules (H₂O) remain the same; they just change from liquid to gas state. No new substance is formed. You can reverse this change by condensing the steam back into liquid water. The chemical identity of the substance remains unchanged throughout the process.

ማብራሪያ (Amharic): ውሃ መፍላት እና ወደ እንፋሎት መቀየር አካላዊ ለውጥ (physical change) ነው ምክንያቱም የውሃ ሞለኪውሎች (H₂O) አይለወጡም፤ ከፈሳሽ ወደ ጋዝ ሁኔታ ብቻ ይለወጣሉ። ምንም አዲስ ንጥረ ነገር አይፈጠርም።

Question 20

Which of the following is NOT a chemical change?

A) Burning of gasoline

B) Souring of milk

C) Cutting a piece of wood

D) Explosion of a firecracker

Correct Answer: C

Explanation (English): Cutting wood is a physical change because the wood is still wood - only its size and shape have changed. No new substances are formed. Burning gasoline, souring milk, and exploding a firecracker all involve chemical reactions that produce new substances with different properties (gases, new compounds, etc.).

ማብራሪያ (Amharic): እንጨት መቁረጥ አካላዊ ለውጥ (physical change) ነው ምክንያቱም እንጨቱ አሁንም እንጨት ነው - መጠኑ እና ቅርጹ ብቻ ተለውጧል። ምንም አዲስ ንጥረ ነገር አልተፈጠረም። ቤንዚን ማቃጠል፣ ወተት ማብላላት እና ርችት ማፈንዳት ኬሚካላዊ ለውጦች ናቸው።

📊 PART 4: EXTENSIVE AND INTENSIVE PROPERTIES

Question 21

Which of the following properties is extensive?

A) Temperature

B) Density

C) Mass

D) Color

Correct Answer: C

Explanation (English): Mass is an extensive property because it depends on the amount of matter present. A gallon of milk has more mass than a cup of milk. In contrast, temperature, density, and color are intensive properties - they remain the same regardless of how much matter you have (a drop of coffee and a pot of coffee can both be at 70°C).

ማብራሪያ (Amharic): ክብደት (mass) ሰፊ ባህሪ (extensive property) ነው ምክንያቱም ባለው የማትሪያ መጠን ይወሰናል። አንድ ጋሎን ወተት ከአንድ ኩባያ ወተት የበለጠ ክብደት አለው። የሙቀት መጠን፣ ጥግግት እና ቀለም ጠንካራ ባህሪያት (intensive properties) ናቸው።

Question 22

If you have a glass of water at 25°C and pour half of it into another glass, the temperature of the water in each glass will be:

A) 12.5°C

B) 25°C

C) 50°C

D) Dependent on the size of the new glass

Correct Answer: B

Explanation (English): Temperature is an intensive property - it does not depend on the amount of substance. When you divide the water, each portion remains at the same temperature (25°C). This is different from extensive properties like volume or mass, which would be halved. The temperature is a measure of the average kinetic energy of molecules, which doesn't change when you split the sample.

ማብራሪያ (Amharic): የሙቀት መጠን (temperature) ጠንካራ ባህሪ (intensive property) ነው - በማትሪያው መጠን አይወሰንም። ውሃውን ሲከፋፍሉት እያንዳንዱ ክፍል አሁንም በ25°C ይቆያል። ይህ እንደ ስፋት ወይም ክብደት ካሉ ሰፊ ባህሪያት የተለየ ነው።

Question 23

Which of the following pairs consists of one extensive and one intensive property?

A) Mass and volume (both extensive)

B) Temperature and density (both intensive)

C) Volume and temperature (extensive and intensive)

D) Color and odor (both intensive)

Correct Answer: C

Explanation (English): Volume is an extensive property (depends on amount of matter), while temperature is an intensive property (does not depend on amount). Option A has two extensive properties, option B has two intensive properties, and option D has two intensive properties. Only option C correctly pairs one extensive and one intensive property.

ማብራሪያ (Amharic): ስፋት (volume) ሰፊ ባህሪ (extensive) ሲሆን የሙቀት መጠን (temperature) ጠንካራ ባህሪ (intensive) ነው። ሌሎቹ አማራጮች ሁለት ሰፊ ወይም ሁለት ጠንካራ ባህሪያትን ይይዛሉ።

Question 24

You have a 100g sample of iron with density 7.87 g/cm³. If you cut it in half, what will be the density of each half?

A) 3.94 g/cm³

B) 7.87 g/cm³

C) 15.74 g/cm³

D) It depends on the shape of the half

Correct Answer: B

Explanation (English): Density is an intensive property - it does not change when you divide a substance. The density of iron is always 7.87 g/cm³ regardless of sample size. While the mass and volume of each half would be half the original, their ratio (mass/volume = density) remains constant because both mass and volume are extensive properties that change proportionally.

ማብራሪያ (Amharic): ጥግግት (density) ጠንካራ ባህሪ ነው - ማትሪያውን ሲከፋፍሉት አይለወጥም። የብረት ጥግግት ሁልጊዜ 7.87 g/cm³ ነው። ክብደቱ እና ስፋቱ ቢቀንሱም ጥግግቱ ግን አይለወጥም።

📏 PART 5: MEASUREMENTS AND UNITS

Question 25

What is the SI base unit for mass?

A) Gram

B) Kilogram

C) Pound

D) Milligram

Correct Answer: B

Explanation (English): The SI base unit for mass is the kilogram (kg) . While we often use grams in the laboratory, the official SI base unit is the kilogram. One kilogram is approximately 2.2 pounds. The gram (g) is actually 1/1000 of a kilogram (10⁻³ kg). The kilogram was originally defined as the mass of one liter of water and is now defined using fundamental physical constants.

ማብራሪያ (Amharic): የSI መሠረታዊ የክብደት አሃድ ኪሎግራም (kg) ነው። በቤተ ሙከራ ውስጥ ግራምን ብንጠቀምም ኦፊሴላዊው የSI አሃድ ኪሎግራም ነው። አንድ ኪሎግራም 2.2 ፓውንድ ያህል ነው።

Question 26

Which prefix means one-thousandth (1/1000 or 10⁻³)?

A) Centi-

B) Milli-

C) Kilo-

D) Micro-

Correct Answer: B

Explanation (English): The prefix milli- means 10⁻³ or one-thousandth. For example, 1 millimeter (mm) = 0.001 meter, and 1 milligram (mg) = 0.001 gram. Centi- (c) means 10⁻² (1/100), kilo- (k) means 10³ (1000), and micro- (μ) means 10⁻⁶ (one-millionth).

ማብራሪያ (Amharic): ሚሊ- የሚለው ቅድመ ቅጥያ 10⁻³ ወይም ከሺህ አንድ ማለት ነው። ለምሳሌ 1 ሚሊሜትር (mm) = 0.001 ሜትር፣ እና 1 ሚሊግራም (mg) = 0.001 ግራም።

Question 27

A cube with edge length of exactly one decimeter (0.1 m) contains a volume of:

A) 1 cubic meter (m³)

B) 1 liter (L)

C) 1 milliliter (mL)

D) 1 cubic centimeter (cm³)

Correct Answer: B

Explanation (English): A cube with edge length of exactly one decimeter (10 cm) has a volume of one cubic decimeter (dm³), which is commonly called one liter (L) . One liter is equivalent to 1000 milliliters (mL) or 1000 cubic centimeters (cm³). A cubic centimeter (cm³) is the volume of a cube with 1 cm edges and is equivalent to 1 mL.

ማብራሪያ (Amharic): አንድ ዲሲሜትር (10 ሳንቲሜትር) ርዝመት ያለው ኩብ አንድ ኪዩቢክ ዲሲሜትር (dm³) ስፋት አለው፣ ይህም አንድ ሊትር (L) ይባላል። አንድ ሊትር 1000 ሚሊሊትር (mL) ወይም 1000 ኪዩቢክ ሳንቲሜትር (cm³) ነው።

Question 28

What is the density of a substance if a 50.0 g sample occupies a volume of 25.0 cm³?

A) 0.5 g/cm³

B) 2.0 g/cm³

C) 1250 g/cm³

D) 75.0 g/cm³

Correct Answer: B

Explanation (English): Density is calculated using the formula: density = mass/volume. Here, mass = 50.0 g and volume = 25.0 cm³. So, density = 50.0 g / 25.0 cm³ = 2.0 g/cm³. This means each cubic centimeter of this substance has a mass of 2.0 grams. This value is reasonable for many solids and liquids (water is 1.0 g/cm³).

ማብራሪያ (Amharic): ጥግግት በቀመር ይሰላል፦ ጥግግት = ክብደት/ስፋት። እዚህ ላይ ክብደት = 50.0 g እና ስፋት = 25.0 cm³። ስለዚህ ጥግግት = 50.0 g / 25.0 cm³ = 2.0 g/cm³።

part one

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