Chemistry For Std. VI (Int'l) : (For Final Term Examination)
Chemistry For Std. VI (Int'l) : (For Final Term Examination)
Chemistry For Std. VI (Int'l) : (For Final Term Examination)
VI (Int’l)
(For Final Term Examination)
Reference Book
Cambridge Lower Secondary Science (Learner’s) Book 7
By Mary Jones, Diane Fellowes-Freeman & Michael Smyth
Properties of Alloys
Resistance to corrosion: Some alloys are more resistant to corrosion, meaning they don’t rust as
easily as other metals or alloys. Example: bronze.
Strength: Some alloys are stronger or weaker than common metals. Stronger alloys are harder to
bend/stretch whereas weaker alloys bend with ease. Example: steel.
Weight: Some alloys are lighter or heavier than other metals or alloys. Difference in weight
allow for alloys to be a good choice when building specific things. Example: duralumin (light).
Resistance to heat: Some alloys have heat resistance capabilities, meaning they can withstand
higher heats than other metals or alloys. Example: stainless steel.
Conductivity: Some alloys have conductivity capabilities, meaning they are able to better at
conducting electricity compared to other metals or alloys. Example: brass.
Amalgam is an alloy of mercury with one or more metals. Sodium along with liquid mercury is
known as sodium amalgam. The amalgam contains about 50% mercury plus silver, copper, tin
and zinc. Amalgam of mercury with tin, silver and zinc is widely used in dental filling.
Steel
Steel is an alloy, but an unusual one because one of the elements in the mixture is not a metal.
Steel is a mixture of iron and carbon. Pure iron is not hard enough to be very useful but when it
is mixed with other elements to form steel it is much harder.
Bronze Brass
Composed of copper and tin Composed of copper and zinc
Reddish-brown in color Bright golden in color
Hard and brittle High degree of malleability
Used in the production of boat and ship Used for decorative purposes
fittings
Resistant to corrosions that occur from salt Corrosion resistant, but not towards salt water
water
Evaporation
Distillation (simple and fractional)
Filtration
Chromatography
Crystallization etc.
Making Mixtures
Mixture contains different substances that are not combined together chemically. You made a
mixture with iron filings and sulfur in topic 2.7. you separated the iron and sulfur in your mixture
by using a magnet. You used the difference in the properties of iron and sulfur to separate them.
Iron is magnetic, sulfur is not magnetic.
Separating Mixtures
Sand and Water - Filtration: The insoluble solid particles can’t pass through the tiny gaps in
the filter paper, but the liquid particles can. As a result, the solid (called the residue) remains in
the filter paper, separated from the remaining liquid or solution which has passed through the
filter paper. This liquid is termed the filtrate.
Figure: Filtration Process
Copper sulfate and water: The evaporating dish contains a mixture of water and copper sulfate.
If it is left in a warm room, the water evaporates and leaves the copper sulfate behind in the dish.
Food dye and water: A mixture of food dye and water can be separated by using a piece of
apparatus called a condenser. It is used to separate mixtures of two liquids.
The water and food dye mixture is heated and boils. The liquid water reaches the temperature
where it changes state and becomes a gas. Water that is in the gas state is called steam when it
has been formed by boiling the water. The gas travels along the tube into the condenser. The cold
water that is circulating around the outside of the condenser cools the gas down. This makes the
gas condense back into liquid water. The liquid water collects in the beaker. The food dye
remains in the heated container.
The food dye and water have different properties that allow you to separate them – they have
different boiling points.
Properties of Acids
Proton Donors: According to the Brønsted-Lowry definition, acids are substances that donate
protons (H⁺ ions) to other substances.
Example: Hydrochloric acid (HCl) donates a proton to water to form hydronium ions (H₃O⁺).
Electron-Pair Acceptors: According to the Lewis definition, acids are substances that can
accept an electron pair.
Example: Boron trifluoride (BF₃) accepts an electron pair from ammonia (NH₃).
pH Level: Acids have a pH level less than 7. The lower the pH, the stronger the acid.
Example: Sulfuric acid (H₂SO₄) has a very low pH and is a strong acid.
Types of Acids
Strong Acids: Completely dissociate in water, releasing a large number of H⁺ ions.
Examples: Hydrochloric acid (HCl), sulfuric acid (H₂SO₄), and nitric acid (HNO₃).
Weak Acids: Partially dissociate in water, releasing fewer H⁺ ions.
Examples: Acetic acid (CH₃COOH), formic acid (HCOOH), and citric acid (C₆H₈O₇).
Organic Acids: Contain carbon and are typically weak acids.
Examples: Acetic acid (CH₃COOH), lactic acid (C₃H₆O₃), and citric acid (C₆H₈O₇).
Mineral (Inorganic Acids): Do not contain carbon and are often strong acids.
Examples: Hydrochloric acid (HCl), sulfuric acid (H₂SO₄), and phosphoric acid (H₃PO₄).
Common Acids and Their Uses
Hydrochloric acid (HCl): Used in the production of chlorides, refining ore, and cleaning
metals.
Sulfuric acid (H2SO4): Used in battery acid, fertilizer production, and chemical synthesis.
Nitric acid (HNO3): Used in the production of fertilizers, explosives, and in metal processing.
Acetic acid (CH3COOH): Used in vinegar, as a solvent, and in the production of polymers.
Citric acid (C6H8O7): Used as a preservative, flavoring agent in foods and beverages, and in
cleaning products.
Phosphoric acid (H3PO4): Used in soft drinks, fertilizers, and rust removal.
Acids play a crucial role in various chemical processes, industrial applications, and everyday
products, making them fundamental to both scientific research and practical applications.
Alkalis
In chemistry, alkalis are a subset of bases that are soluble in water. They can neutralize acids to
form salt and water and are typically characterized by their slippery feel, bitter taste, and ability
to turn red litmus paper blue. Here are some key points about alkalis:
Properties of Alkalis
Hydroxide ion production: Alkalis dissociate in water to produce hydroxide ions (OH⁻).
Example: Sodium hydroxide (NaOH) dissociates in water to form Na⁺ and OH⁻ ions.
pH Level: Alkalis have a pH level greater than 7. The higher the pH, the stronger the alkali.
Example: A solution of potassium hydroxide (KOH) has a high pH, indicating it is a strong
alkali.
Types of Alkalis
Strong Alkalis: Fully dissociate in water, producing a high concentration of hydroxide ions.
Examples: Sodium hydroxide (NaOH), potassium hydroxide (KOH), and calcium hydroxide
(Ca(OH)2).
Weak Alkalis: Partially dissociate in water, producing a lower concentration of hydroxide ions.
Examples: Ammonium hydroxide (NH4OH), magnesium hydroxide (Mg(OH)2).
Safety Considerations
Handling: Strong alkalis are corrosive and can cause burns upon contact with skin or eyes.
Proper safety equipment such as gloves and goggles should be used.
Storage: Alkalis should be stored in tightly sealed containers to prevent them from absorbing
moisture and CO2 from the air, which can weaken their effectiveness.
Alkalis play a crucial role in various industrial, household, and medical applications due to their
ability to neutralize acids, their cleaning properties, and their reactivity with organic and
inorganic substances.
Hazardous Symbols
In chemistry, hazardous symbols are used to indicate the dangers associated with chemicals and
substances, ensuring safe handling, storage, and use. These symbols are standardized to convey
specific hazards and are recognized internationally. The most commonly used system is the
Globally Harmonized System of Classification and Labelling of Chemicals (GHS), which
includes pictograms with a distinct black symbol on a white background with a red diamond
border. Here are the main GHS hazard symbols:
Description: Indicates that the gas is stored under pressure and can explode if heated.
Examples: Compressed air, liquefied petroleum gas (LPG).
Precautions: Store in well-ventilated areas away from heat sources.
Corrosive (Symbol: Corrosion)
Description: Indicates that the substance can cause severe skin burns and eye damage, and can
corrode metals.
Examples: Hydrochloric acid, sodium hydroxide.
Precautions: Use protective clothing, gloves, and eye protection.
Description: Indicates that the substance can cause serious health effects or death if inhaled,
ingested, or absorbed through the skin.
Examples: Cyanide, arsenic.
Precautions: Avoid all contact and use appropriate protective equipment.
Harmful/Irritant (Symbol: Exclamation Mark)
Description: Indicates that the substance can cause health effects such as skin irritation,
respiratory issues, or eye damage.
Examples: Acetone, turpentine.
Precautions: Use protective clothing and ensure good ventilation.
Description: Indicates that the substance may cause serious long-term health effects such as
carcinogenicity, respiratory sensitization, or reproductive toxicity.
Examples: Asbestos, formaldehyde.
Precautions: Use protective equipment and handle with care
Environmental Hazard (Symbol: Environment)
Description: Indicates that the substance can cause damage to the aquatic environment and
ecosystem.
Examples: Mercury, pesticides.
Precautions: Prevent release into the environment and follow proper disposal protocols.
Indicator
In chemistry, an indicator is a substance that changes color in response to a change in pH, which
makes it useful for determining the acidity or basicity of a solution. Indicators are typically used
in titrations to signal the endpoint of the reaction, but they can also be used to measure pH in
various experimental settings.
Types of Indicators
pH indicators: These indicators exhibit different colors at different pH levels. They are usually
weak acids or bases where the dissociated form is a different color than the undissociated form.
Examples of pH indicators:
Litmus: Turns red in acidic solutions (pH < 7) and blue in basic solutions (pH > 7).
Phenolphthalein: Colorless in acidic solutions and turns pink in basic solutions (pH > 8.2).
Methyl orange: Red in acidic solutions (pH < 3.1) and yellow in basic solutions (pH > 4.4).
Bromothymol blue: Yellow in acidic solutions (pH < 6.0) and blue in basic solutions (pH >
7.6).
Universal indicator: A mixture of several indicators that provides a gradual color change over a
wide pH range (typically 1 to 14). It gives an approximate pH value of the solution.
Color range
Red (pH 1-3, strong acid)
Orange/Yellow (pH 4-6, weak acid)
Green (pH 7, neutral)
Blue (pH 8-11, weak base)
Purple (pH 12-14, strong base)
Application of Indicators
Titration: Indicators are commonly used in acid-base titrations to determine the endpoint,
where the amount of acid equals the amount of base in the solution.
Example: Phenolphthalein is often used in titrations of strong acids with strong bases because it
changes color at a pH around the equivalence point (around pH 8.2).
Measuring pH: Indicators can be used to measure the pH of a solution by comparing the color
change to a standard pH color chart.
Example: Using pH paper or a universal indicator solution to determine the pH of household
substances like vinegar or baking soda solutions.
Biological and environmental science: Indicators are used to monitor the pH of natural water
bodies, soils, and biological fluids, as pH is a critical factor in many biological and ecological
processes.
Example: Bromothymol blue is used in aquatic science to study photosynthesis and respiration
in water bodies.
Litmus Test
The litmus test is a simple and widely used chemical test to determine the acidity or basicity of a
solution. It employs litmus paper, which is treated with a dye that changes color in response to
the pH of the solution it contacts. Litmus paper comes in two types: red and blue.
How the Litmus Test Works
Litmus paper is infused with a natural dye extracted from lichens, primarily from the genus
Roccella. This dye exhibits different colors in acidic and basic environments:
Red litmus paper: Turns blue in the presence of a base (alkaline solution).
Blue litmus paper: Turns red in the presence of an acid.
Figure: Litmus Test to Identify Acids and Alkalis
Procedure for Conducting a Litmus Test
Selecting the litmus paper
Use red litmus paper to test for basicity.
Use blue litmus paper to test for acidity.
pH and pH Scale
The pH scale is a numerical scale used to specify the acidity or basicity (alkalinity) of an
aqueous solution. It is an important concept in chemistry, biology, and environmental science.
Definition of pH: pH is defined as the negative logarithm (base 10) of the hydrogen ion
concentration [H+] in a solution:
pH = − log [H+]
Where, [H+] is the molar concentration of hydrogen ions in the solution.
Also, for alkalis, pOH = - log [OH-]
And, pH + pOH = 14
pH Scale
The pH scale typically ranges from 0 to 14:
Acidic solution: pH < 7
Neutral solutions: pH = 7
Alkaline solution: pH > 7
Calculating pH
To calculate the pH of a solution, you need to know the concentration of hydrogen ions. For
example:
Strong acid: 0.01 M HCl pH = − log [H+]
Or, pH = − log (0.01)
=2
Strong alkali: 0.001 M NaOH First, calculate the concentration of hydroxide ions [OH−],
[OH−] = 0.001 M
pOH = - log 0.001
=3
pH = 14 – pOH
= 14 – 3
= 11
Importance of pH
Biological system: Enzymes and biochemical processes in living organisms are highly sensitive
to pH. Human blood, for example, is tightly regulated around pH 7.4.
Environmental science: The pH of water bodies affects aquatic life. Acid rain, with a low pH,
can harm ecosystems.
Agriculture: Soil pH affects nutrient availability for plants. Most crops prefer a slightly acidic to
neutral pH.
Industrial applications: pH is crucial in processes like fermentation, water treatment, and
chemical manufacturing.
Measuring pH
pH indicators: Substances that change color at specific pH levels (e.g., litmus paper,
phenolphthalein)
pH meter: An electronic device that measures pH more accurately using a probe that senses
hydrogen ion activity.
Figure: pH Meter
Universal indicator: A mixture of indicators that provide a color change over a wide pH range,
giving an approximate pH value.
The pH scale is a vital tool in chemistry for indicating the acidity or basicity of a solution. It
ranges from 0 to 14, with 7 being neutral. pH is essential in various fields, from biology and
environmental science to industry and agriculture, and is measured using indicators, pH meters,
or universal indicators. Understanding and controlling pH is crucial for many scientific and
practical applications.
Physical Properties
Physical properties are characteristics of a substance that can be observed or measured without
changing its chemical identity. These properties describe the physical attributes and state of a
substance. Key physical properties include:
Color: The color of a substance as observed visually.
Odor: The smell of a substance, detected by the sense of smell.
Density: The mass of a substance per unit volume, typically expressed in grams per cubic
centimeter (g/cm³).
Melting point: The temperature at which a solid turns into a liquid.
Boiling point: The temperature at which a liquid turns into a gas.
Solubility: The ability of a substance to dissolve in a solvent, such as water.
Hardness: The resistance of a substance to being scratched or deformed.
Electrical conductivity: The ability of a substance to conduct electricity.
Thermal conductivity: The ability of a substance to conduct heat.
Magnetism: The ability of a substance to be attracted to a magnet.
State of matter: Whether the substance is a solid, liquid, or gas at a given temperature and
pressure.
Chemical Properties
Chemical properties describe the behavior of a substance when it undergoes a chemical change
or reaction. These properties reveal how a substance interacts with other substances and what
types of chemical bonds it forms or breaks. Key chemical properties include:
Reactivity: How readily a substance undergoes chemical reactions with other substances.
Flammability: The ability of a substance to burn in the presence of oxygen.
pH: The measure of a substance’s ability to donate or accept protons (H⁺ ions) in solution.
Oxidation state: The various charges a substance can have when it forms compounds.
Toxicity: The degree to which a substance can harm living organisms.
Corrosiveness: The ability of a substance to damage or destroy other substances it comes into
contact with through chemical reactions.
Combustibility: The ability of a substance to ignite and burn.
Electronegativity: The tendency of an atom to attract electrons in a chemical bond.
Examples of Chemical Properties
Hydrogen: Highly flammable, reacts explosively with oxygen to form water.
Sodium: Reacts vigorously with water to produce sodium hydroxide and hydrogen gas.
Chlorine: Reacts with metals to form chlorides, toxic and corrosive, strong oxidizing agent.
Changes in Chemistry
There are two types of changes we notice in chemistry. They are: i. Physical change and ii.
Chemical change
Physical change: It is a type of change where the physical properties of matter change. A
change of state of matter, change in color, odor, solubility etc. Melting of ice is an example of
physical change. During a physical change, neither the composition nor the chemical nature of
matter is changed. That means, in physical change no new substance is formed but only the
physical properties of the matter change. Also, physical change is easy to be reversed in its
previous form.
Chemical Reactions
Definition: A process by which one or more substances, called reactants, are changed into one or
more substances, called products, with different physical and chemical properties is called a
chemical reaction.
Colour change
Formation of a precipitate (ppt)
Release of a gas
Energy change (heat, light, sound)
Odour change
Reactants
Definition: Reactants are the substances present at the beginning of a chemical reaction that
undergo a transformation.
Role: Reactants are consumed during the reaction and are converted into products.
Representation: Reactants are typically written on the left-hand side of a chemical equation.
Examples of Reactants
Hydrogen (H2) and oxygen (O2) reacting to form (H2O): 2H2 + O2 → 2H2O (Hydrogen gas
and oxygen gas are the reactants, and water is the product.)
Iron (Fe) reacting with oxygen (O 2) to form iron oxide (Fe2O3): 4Fe + 3O2 → 2Fe2O3 (Iron
and oxygen are the reactants, and iron oxide is the product.)
Products
Definition: Products are the substances formed as a result of a chemical reaction.
Role: Products are created from reactants during the reaction.
Representation: Products are typically written on the right-hand side of a chemical equation.
Examples of Products
Formation of water (H2O) from hydrogen (H2) and oxygen (O2): 2H2 + O2 → 2H2O (Water is
the product formed from the reaction of hydrogen gas and oxygen gas.)
Formation of carbon dioxide (CO2) from methane (CH4) and oxygen (O2): CH4 + 2O2 →
CO2 + 2H2O (Carbon dioxide and water are the products formed from the combustion of methane
gas in oxygen.)
In a chemical reaction, reactants are the starting materials that undergo a chemical change, while
products are the new substances formed as a result of the reaction. Reactants are transformed into
products through the breaking and forming of chemical bonds. Balancing chemical equations
ensures that the number of atoms of each element is the same on both sides of the equation,
reflecting the conservation of mass.
Change the words to symbol and formulas for the reactants and products
H2 + O2 H2O
Count the number of each atom both for reactants and products
H2 + O2 H2O
2 hydrogen atoms, 2 oxygen atoms 2 hydrogen atoms and 1 oxygen atom
Multiply the reactants and products with suitable numbers to balance the equation
2H2 + 2H2O
O2
Check the balanced equation
2H2 + O2 2H2O
4 hydrogen atoms and 2 oxygen 4 hydrogen atoms and 2 oxygen atoms
atoms
Note: We can also calculate the mass numbers to balance the chemical equation.
Generally, gases are diatomic molecules, and their molecular form should be written in a
chemical equation. For metals, we use only the symbol.
Figure: Balancing a chemical equation (formation of water)
Burning
In chemistry, burning, also known as combustion, is a chemical reaction between a fuel and an
oxidant (usually oxygen) that produces heat and light. This exothermic reaction typically
involves the rapid combination of a substance with oxygen, resulting in the formation of oxides
and the release of energy.
Types of Combustion
Complete combustion: Occurs when there is a sufficient supply of oxygen. Produces carbon
dioxide (CO2) and water (H2O).
Example: CH4 + 2O2 → CO2 + 2H2O + Energy (Methane burning in oxygen)
Incomplete combustion: Occurs when there is an insufficient supply of oxygen. Produces
carbon monoxide (CO), soot (carbon, C), and water.
Example: 2CH4 + 3O2 → 2CO + 4H2O + Energy (Methane burning with limited oxygen)
Note: CO is also called silent killer gas.
8.2 Neutralization
Mixing Acids and Alkalis
Mixing acids and alkalis (bases) together can result in a chemical reaction known as
neutralization. This reaction occurs between the hydrogen ions (H ⁺) from the acid and the
hydroxide ions (OH⁻) from the alkali to form water and a salt. The salt formed depends on the
specific acid and alkali involved in the reaction.
Neutralization Reaction:
Acid + Alkali → Salt + Water
Example:
HCl (Hydrochloric Acid) + NaOH (Sodium Hydroxide) → NaCl (Sodium Chloride) + H2O
Key Points:
Formation of water: The hydrogen ions (H⁺) from the acid combine with the hydroxide ions
(OH⁻) from the alkali to form water (H2O).
Formation of salt: The remaining ions from the acid and alkali combine to form a salt. The
specific salt formed depends on the ions present in the acid and alkali.
Neutralization: The resulting solution is typically neutral in pH, meaning it has a pH close to 7.
This is because the acidic and basic properties of the acid and alkali cancel each other out.
Examples of Neutralization Reactions:
Reaction of hydrochloric acid (HCl) with sodium hydroxide (NaOH):
HCl + NaOH → NaCl + H2O (Forms sodium chloride, commonly known as table salt)
Reaction of sulfuric acid (H2SO4) with potassium hydroxide (KOH):
H2SO4 + 2KOH → K2SO4 + 2H2O (Forms potassium sulfate and water)
Applications
Wastewater treatment: Acids and alkalis are often used to neutralize acidic or basic wastewater
before it is discharged into the environment.
Antacid medications: Antacids containing bases are used to neutralize excess stomach acid to
relieve symptoms of indigestion or heartburn.
Safety Considerations
Some neutralization reactions can generate heat, especially when concentrated acids and alkalis
are mixed. Care should be taken to avoid splashing and ensure proper ventilation.
Always handle concentrated acids and alkalis with care, wearing appropriate personal protective
equipment such as gloves and goggles.
Procedure
Safety precautions: Wear appropriate personal protective equipment, including gloves and
safety goggles, when handling acids and bases.
Work in a well-ventilated area to avoid inhaling any fumes.
Prepare acid and alkali solutions: Dilute the concentrated acid and base solutions to a known
concentration using distilled water. Use a volumetric flask or graduated cylinder to measure the
volumes accurately.
Determine required amounts: Calculate the volumes of acid and base solutions needed to
achieve a neutral solution. This depends on the concentrations of the solutions and the
stoichiometry of the neutralization reaction.
Mix acid and alkali: In a clean beaker, carefully pour the measured volumes of the acid and
base solutions. Stir the mixture gently with a stirring rod to ensure thorough mixing.
Monitor pH: Use a pH meter or pH paper to measure the pH of the solution. Continue adding
small amounts of acid or base as needed to adjust the pH closer to 7 if necessary.
Final adjustment: Once the pH is close to 7, stop adding acid or base and recheck the pH. Make
any final adjustments if needed to ensure the solution is truly neutral.
Final dilution (optional): If the concentration of the neutral solution needs to be adjusted, dilute
it with additional distilled water as necessary.
Label and store: Label the container with the contents and concentration of the neutral solution.
Store it in a properly labeled and sealed container for future use.
Safety Considerations:
Handle acids and bases with care, following appropriate safety precautions. Avoid mixing
concentrated acids and bases directly, as they can react violently and release heat. Work in a
well-ventilated area to avoid inhaling fumes.
By following this procedure and carefully controlling the amounts of acid and base added, you
can prepare a neutral solution with a pH close to 7.
Antacid Medications
Problem: Excess stomach acid can cause discomfort and heartburn.
Solution: Antacid medications contain bases that neutralize stomach acid, providing relief from
indigestion and heartburn.
Example: Magnesium hydroxide and aluminum hydroxide are commonly used antacids that
react with stomach acid to form water and salts, thereby neutralizing the acidity.
Soil Treatment in Agriculture
Problem: Some soils are too acidic for optimal plant growth.
Solution: Lime (calcium carbonate or calcium hydroxide), which is alkaline, is added to acidic
soils to neutralize the acidity and improve soil fertility.
Example: The neutralization reaction between lime and soil acids forms water and salts, helping
to raise the soil pH to a more favorable range for plant growth.
Wastewater Treatment
Problem: Industrial wastewater often contains acidic or basic pollutants.
Solution: Neutralization is used to adjust the pH of wastewater before it is discharged into the
environment.
Example: Acids or bases are added to acidic or basic wastewater to neutralize the pH, making it
less harmful to the environment.
Baking
Problem: Excess acidity in baked goods can affect flavor and texture.
Solution: Baking soda (sodium bicarbonate) is a common ingredient used to neutralize acidity in
recipes.
Example: Baking soda reacts with acidic ingredients such as vinegar or buttermilk to produce
carbon dioxide gas, which helps baked goods rise. The resulting salt is neutral in flavor.
Swimming Pool Maintenance
Problem: Chlorine used to disinfect swimming pools can lower the pH of the water, making it
acidic.
Solution: Pool owners use alkaline substances such as sodium bicarbonate (baking soda) or
sodium carbonate (soda ash) to raise the pH and neutralize acidity.
Example: Adding baking soda to a swimming pool reacts with excess hydrogen ions (H ⁺) from
the acidic water, raising the pH to a more suitable level for swimming.
Cleaning Products:
Problem: Some cleaning products are acidic or basic, which can be harsh or corrosive.
Solution: Neutralizing agents are added to cleaning products to make them less acidic or basic,
reducing their potential for damage.
Example: Neutralizing acids or bases with appropriate chemicals results in pH-balanced
cleaning products that are safer for use on surfaces.
In each of these examples, neutralization reactions are used to balance acidity and alkalinity,
providing practical solutions to common problems encountered in daily life.
5.3-5.6
MCQ 01. Alloys are_____
A Metal mixtures C Gas-gas mixture
B Non-metal mixtures D Salt-salt mixture
Answer: A
MCQ 02. Brass is an alloy of_____
A Zinc C Copper
B Tin D Iron
Answer: C
MCQ 03. Bronze contains ______
A Copper and Zinc C Iron and Zinc
B Copper and Tin D Zinc and Titanium
Answer: B
MCQ 04. Which of the following is an alloy but contains a non-metal?
A Duralumin C Brass
B Solder D Steel
Answer: D
MCQ 05. Main component of pewter is ________
A Tin C Zinc
B Iron D Nickel
Answer: A
MCQ 06. In modern bronze, percentage of tin is ___________
A 88% C 66%
B 12% D 34%
Answer: B
MCQ 07. Which of the following is not a separation technique?
A Masking C Filtration
B Evaporation D Chromatography
Answer: A
MCQ 08. The clear liquid obtained after filtration is called _______
A Residue C Filtrate
B Crystal D Evaporation
Answer: C
MCQ 09. The solid obtained in the filter paper after filtration is called __________
A Residue C Crystal
B Filtrate D Evaporation
Answer: A
MCQ 10. Which of the following is not a property of acids?
A Proton donor C pH is less than 7
B Electron-pair acceptor D pH is more than 7
Answer: D
MCQ 11. Which of the following is not a property of alkali?
A Hydroxide ion production C pH is more than 7
B Proton donor D Proton acceptor
Answer: B
MCQ 12. Z is an acid. It can donate______
A OH- C H+
B SO42- D H
Answer: C
MCQ 13. Which of the following is not a strong acid?
A Hydrochloric acid C Acetic acid
B Nitric acid D Sulfuric acid
Answer: C
MCQ 14. Which of the following is a mineral acid?
A Citric acid C Lactic acid
B Phosphoric acid D Acetic acid
Answer: B
MCQ 15. Which acid is used in vinegar?
A Hydrochloric acid C Acetic acid
B Citric acid D Lactic acid
Answer: C
MCQ 16. What is the chemical formula of sulfuric acid?
A HCl C HClO4
B HNO3 D H2SO4
Answer: D
MCQ 17. pH of an alkali can be __________
A 3.8 C 8.9
B 7.0 D 5.5
Answer: C
MCQ 18. A solution has a pH of 11.5. It is an________
A Acid C Neutral solution
B Alkali D Salt
Answer: B
MCQ 19. KOH is an ______
A Alkali C Salt
B Acid D None of them
Answer: A
MCQ 20. Which of the following is used in soap making?
A Potassium C Sodium hydroxide
B Sodium D Sodium chloride
Answer: C
MCQ 21. The following symbol indicates ________ hazardous symbol.
A Toxic C Irritant
B Corrosive D Health hazard
Answer: A
MCQ 22. Pure water is ____________
A Acidic C Neutral
B Alkaline D None of them
Answer: C
MCQ 23. Acids and alkalis react together to form ________ and water.
A Rust C Steam
B Salt D Oxygen
Answer: B
MCQ 24. A solution turns red litmus into blue. That solution is _________
A A gas C Alkaline
B Neutral D Acidic
Answer: C
MCQ 25. What will be the color change of a red litmus paper in pure water?
A It will turn into blue C It will turn into green
B It will turn into white D It will remain red
Answer: D
MCQ 26. Phenolphthalein is ______ in acidic medium.
A Colorless C Red
B Pink D Yellow
Answer: A
MCQ 27. What is the pH of 0.01M HCl solution?
A 1 C 3
B 2 D 4
Answer: B
MCQ 28. What is the color of universal indicator in an acid solution?
A Green C Pink
B Red D Violet
Answer: B
MCQ 29. pH + pOH = ?
A 10 C 0
B 1 D 14
Answer: D
MCQ 30. Methyl red is ______ in color in alkaline solution.
A Red C Yellow
B Colorless D Pink
Answer: C
Chapter-8
MCQ 01. Which of the following is not a physical property?
A Color C Toxicity
B Odor D Magnetism
Answer: C
MCQ 02. pH is a ________ property.
A Physical C Analytical
B Chemical D None of them
Answer: B
MCQ 03. In a physical change, ____________ is changed.
A Physical state C Nucleus of atoms
B Chemical composition D Chemical formula
Answer: A
MCQ 04. Rusting of iron is an example of _________
A Chemical change C Melting
B Physical change D Boiling
Answer: A
MCQ 05. Reactants are written on the ______ side of the arrow sign in a chemical reaction.
A Upper C Left
B Down D Right
Answer: C
MCQ 06. 2H2 + O2 = 2H2O. Which one the product here?
A H2 C H2O
B O2 D None of these
Answer: C
MCQ 07. In incomplete combustion, ________ is formed.
A Carbon monoxide C Oxygen
B Carbon dioxide D Calcium carbonate
Answer: A
MCQ 08. Carbon monoxide is also called _______ gas.
A Major greenhouse C IR active
B Silent killer D None of these
Answer: B
MCQ 09. An alkaline chemical is produced when potassium reacts with water. What is that
compound?
A Hydrochloric acid C Potassium chloride
B Water D Potassium hydroxide
Answer: D
MCQ 10. When 1 mole hydrogen ion reacts with 1 mole hydroxide ion, it forms _________
A Salt C Water
B Soap D Oxygen
Answer: C
MCQ 11. Antacid contains an ______
A Acid C Salt
B Alkali D Water
Answer: B
MCQ 12. A neutral solution can be prepared by the addition of _______
A Acid and water C Alkali and a neutral gas
B Alkali and water D Acid and alkali
Answer: D
MCQ 13. Which test is not suitable for acid-alkali test?
A Litmus test C TDS test
B pH test D Universal indicator test
Answer: C
MCQ 14. If you add 2-3 drops universal indicator in an alkaline solution, the color will
turn into __________.
A Red C Purple
B Blue D B or C
Answer: D
MCQ 15. When you add vinegar in baking powder, a gas is evolved. What is that gas?
A Carbon dioxide C Carbon monoxide
B Oxygen D Hydrogen
Answer: A
MCQ 16. pH of a neutral solution is _________
A 5.5 C 8.5
B 7.0 D 14
Answer: B
MCQ 17. CaCO3 is also called ________
A Quicklime C Limestone
B Limewater D Lime
Answer: C
MCQ 18. Which of the following is flammable?
A Hydrogen gas C Oxygen gas
B Carbon dioxide gas D None of them
Answer: A
MCQ 19. Which of the following is a neutral chemical?
A HCl C KOH
B H2O D NaOH
Answer: B
MCQ 20. Which of the following is a salt?
A H2O C ZnCl2
B KOH D HCl
Answer: C