All Courses
Get the App Signup / Login
Sign in Open App
All Exams  >   Class 9  >   Sample Papers For Class 9  >   All Questions

All questions of Science for Class 9 Exam

Clear all your doubts with EduRev

The substance found in the cell wall of cork or bark that makes it impervious to water is
  • a)
    cutin
  • b)
    lignin
  • c)
    suberin
  • d)
    lipids
Correct answer is option 'C'. Can you explain this answer?

Aditi Sharma answered
The cork is impervious to water due to suberin deposition in the cell wall of its cells. The walls of cork cells are heavily thickened with an organic substance, suberin. Suberin makes these cells impervious to water and gases.

Match the following with correct response.
  • a)
    1-C, 2-B, 3-D, 4-A
  • b)
    1-B, 2-D. 3-A, 4-C
  • c)
    1-D, 2-A, 3-C, 4-B
  • d)
    1-A, 2-C, 3-B, 4-D
Correct answer is option 'B'. Can you explain this answer?

Aditi Sharma answered
1- B In mixtures the components do not lose their properties.
2- D In a compound the constituent elements combine in fixed proportion by mass.
3 - A Elements are made up of same kind of atoms & elements can not be further broken down.
4 - C An atom is the smallest unit of matter that has the properties of an element.

The cell walls of collenehyma tissues are unevenly thickened due to
  • a)
    Both cellulose and pectin
  • b)
    Pectin
  • c)
    Lignin
  • d)
    Cellulose
Correct answer is option 'A'. Can you explain this answer?

Swati Verma answered
The collenchyma is the typical supporting tissue of the primary plant body and growing plant parts, though it is kept with unaltered structure and function even in outgrown organs like stems, petioles, laminae or roots. The walls of collenchyma cells are strengthened by the deposit of cellulose and the coating with pectin. These strengthenings are often restricted to single parts or edges of the cell.

Read the text carefully and answer the questions:
Cell organelles are enclosed by membranes. Cell organelles are the endoplasmic reticulum, Golgi apparatus, lysosomes, mitochondria and plastids. The endoplasmic reticulum (ER) is a large network of membrane-bound tubes and sheets. It looks like long tubules or round or oblong bags. There are two types of ER rough endoplasmic reticulum (RER) and smooth endoplasmic reticulum (SER). RER looks rough under a microscope because it has particles called ribosomes attached to its surface. The ribosomes, which are present in all active cells, are the sites of protein manufacture. The Golgi apparatus, first described by Camillo Golgi, consists of a system of membrane-bound vesicles arranged approximately parallel to each other in stacks called cisterns.
Q. Which of the given are covered by a single membrane?
  • a)
    Plastid
  • b)
    Lysosome
  • c)
    Vacuole
  • d)
    Mitochondria
Correct answer is option 'C'. Can you explain this answer?

Swati Verma answered
A lysosome is covered by a single membrane. Lysosomes are an essential cell organelle present inside the eukaryotic animal cells. Due to their function, they are also called as the “suicide bags” of the cell. Lysosomes are single membrane-bound organelles and the region inside the membrane is known as the lumen, which includes the hydrolytic enzymes and other cellular debris.  The vital role of lysosomes is digestion and removal of waste. Cellular debris or foreign particles are pulled into the cell by the process of endocytosis. The process of endocytosis takes place when the cell membrane falls in on itself (invagination), creating a vacuole or a pouch near the external contents and then bringing those contents into the cell.
Vacuole is also a single membrane structure or organelle found in the cytoplasm with varying sizes. Whereas mitochondria given in the option is double membrane bound organelle.
 

Read the text carefully and answer the questions:
A suspension is a heterogeneous mixture in which the solute particles do not dissolve but remain suspended throughout the bulk of the medium. Particles of a suspension are visible to the naked eye. The particles of a suspension scatter a beam of light passing through it and make its path visible. Due to the relatively smaller size of particles, as compared to that of a suspension, the mixture appears to be homogeneous. The scattering of a beam of light is called the Tyndall effect. The components of a colloidal solution are the dispersed phase and the dispersion medium. The solute-like component or the dispersed particles in a colloid form the dispersed phase, and the component in which the dispersed phase is suspended is known as the dispersing medium.
Q. Which of the following is an example of solid sol?
  • a)
    Shaving cream
  • b)
    Fog
  • c)
    Coloured gemstone
  • d)
    Milk
Correct answer is option 'C'. Can you explain this answer?

Ascendry Ok answered
Gemstone is solid and the question asked what is a *solid* sol

A student by mistake mixed iron filings and sulphur powder. He wanted to separate them from each other. The method you would advise him to use it to dissolve the mixture in
  • a)
    carbon disulphide
  • b)
    kerosene
  • c)
    cold water
  • d)
    boiling water
Correct answer is option 'A'. Can you explain this answer?

Swati Verma answered
Addition of carbon disulphide to a mixture containing iron filings and sulphur powder leads to the formation of a clear yellow solution when sulphur powder dissolves in carbon disulphide, on gentle shaking. Iron fillings being insoluble settle in the bottom. These can be separated by filtration. When the solution is allowed to evaporate, the powder of solid sulphur is obtained.

Assertion (A): When astronauts throw something in space, that object would continue moving in the same direction and with the same speed.
Reason (R): The acceleration of an object produced by a net applied force is directly related to the magnitude of the force, and inversely related to the mass of the object.
  • a)
    Both A and R are true and R is the correct explanation of A.
  • b)
    Both A and R are true but R is not the correct explanation of A.
  • c)
    A is true but R is false.
  • d)
    A is false but R is true.
Correct answer is option 'B'. Can you explain this answer?

Yashasvi Reddy answered
**Assertion (A):** When astronauts throw something in space, that object would continue moving in the same direction and with the same speed.

**Reason (R):** The acceleration of an object produced by a net applied force is directly related to the magnitude of the force, and inversely related to the mass of the object.

The correct answer is option 'B' - Both A and R are true but R is not the correct explanation of A.

Explanation:

**Astronauts throwing something in space:**

When astronauts throw something in space, the object will continue moving in the same direction and with the same speed unless acted upon by an external force. This is due to the absence of significant forces such as air resistance or friction in space.

**Acceleration and Net Applied Force:**

The acceleration of an object is directly related to the magnitude of the net applied force and inversely related to the mass of the object. This relationship is described by Newton's second law of motion, which states that the acceleration of an object is equal to the net force acting on it divided by its mass (a = F/m).

In space, when an astronaut throws an object, they apply a force to it. According to Newton's third law of motion, the object exerts an equal and opposite force on the astronaut. As a result, the object accelerates in the direction of the force applied by the astronaut.

**Explanation of the Reason (R):**

The Reason (R) correctly states that the acceleration of an object is directly related to the magnitude of the force and inversely related to the mass of the object. However, it does not provide a direct explanation for why the object would continue moving in the same direction and with the same speed after being thrown in space.

**Conclusion:**

In conclusion, both the Assertion (A) and the Reason (R) are true. However, the Reason (R) does not provide a correct explanation for the Assertion (A). When astronauts throw something in space, the object will continue moving in the same direction and with the same speed due to the absence of significant external forces like air resistance or friction.

Intercalated disc is present in _____.
  • a)
    Both Smooth muscle and Cardiac muscle
  • b)
    Striated muscle
  • c)
    Smooth muscle
  • d)
    Cardiac muscle
Correct answer is option 'D'. Can you explain this answer?

Harshad Chaudhary answered
Intercalated discs in Cardiac Muscle
Intercalated discs are specialized structures that are found in cardiac muscle tissue. These disc-like structures are formed by the joining of adjacent cardiac muscle cells, or cardiomyocytes. They play a crucial role in the function and synchronization of cardiac muscle contractions.

Structure of Intercalated Discs
Intercalated discs consist of three main components:

1. Fascia adherens: This component is found at the lateral edges of the intercalated disc. It is a dense layer of proteins that connects the actin filaments of adjacent cardiac muscle cells. Fascia adherens helps to provide structural support and maintain the alignment of the cells.

2. Desmosomes: Desmosomes are specialized protein complexes that anchor cardiac muscle cells together. They are found throughout the intercalated disc and provide strong mechanical connections between adjacent cells. Desmosomes help to distribute tension and prevent the cells from being pulled apart during contraction.

3. Gap junctions: Gap junctions are small channels that allow for direct communication between adjacent cardiac muscle cells. They are located in the central region of the intercalated disc. Gap junctions facilitate the flow of ions and small molecules, such as calcium and potassium, between cells. This enables the coordination and synchronization of cardiac muscle contractions.

Function of Intercalated Discs
Intercalated discs are essential for the proper functioning of cardiac muscle tissue. They serve several important functions:

1. Mechanical connection: The fascia adherens and desmosomes provide strong mechanical connections between adjacent cardiac muscle cells, allowing for the transmission of force during contraction. This ensures that the heart contracts as a coordinated unit, pumping blood efficiently.

2. Electrical coupling: Gap junctions allow for the rapid spread of electrical impulses between cardiac muscle cells. This enables the synchronized contraction of the heart and ensures that the electrical signals responsible for initiating contractions are efficiently transmitted throughout the tissue.

3. Cellular communication: Gap junctions also allow for the exchange of ions and small molecules between cells. This facilitates the coordination of cellular activities and helps to maintain the proper balance of ions and molecules within the tissue.

Conclusion
Intercalated discs are specialized structures found in cardiac muscle tissue. They consist of fascia adherens, desmosomes, and gap junctions, which provide mechanical connections, electrical coupling, and cellular communication between adjacent cardiac muscle cells. These discs play a vital role in the proper functioning and synchronization of cardiac muscle contractions, allowing for efficient pumping of blood by the heart.

Lignified or thickened cell wall is a characteristic feature of
  • a)
    phloem
  • b)
    xylem
  • c)
    parenchyma
  • d)
    collenchyma
Correct answer is option 'B'. Can you explain this answer?

Swati Verma answered
The xylem is one of the conductive tissues in plants. It is a complex tissue composed of many types of cells. The main function of xylem is to conduct water and minerals from roots to leaves. The secondary xylem also provides mechanical support due to the presence of a thick lignified cell wall.

Assertion (A): Most of plant tissues are dead.
Reason (R): Due to the sedentary existence of plants, dead cells provide mechanical strength more easily than live ones and need less maintenance.
  • a)
    Both A and R are true and R is the correct explanation of A.
  • b)
    Both A and R are true but R is not the correct explanation of A.
  • c)
    A is true but R is false.
  • d)
    A is false but R is true.
Correct answer is option 'A'. Can you explain this answer?

Avinash Patel answered
Assertion (A): Most of plant tissues are dead.
Reason (R): Due to the sedentary existence of plants, dead cells provide mechanical strength more easily than live ones and need less maintenance.
The correct answer is A. Both A and R are true and R is the correct explanation of A.
Explanation:
- Plants have two types of tissues: meristematic tissues and permanent tissues.
- Meristematic tissues are actively dividing cells and are responsible for growth in plants.
- Permanent tissues, on the other hand, are non-dividing cells that provide mechanical support, transport water and nutrients, and store food.
- Most of the permanent tissues in plants are dead, meaning they have lost their metabolic functions.
- The reason for this is that dead cells provide mechanical strength more easily than live ones, as they have rigid cell walls and do not require energy for maintenance.
- Dead cells also provide structural support to the plant, allowing it to stand upright.
- In contrast, live cells are metabolically active and require energy for maintenance and growth.
- The sedentary existence of plants, being rooted in the ground, makes it more advantageous for them to have dead tissues that require less maintenance.
- Therefore, the reason provided in R explains why most plant tissues are dead.

Which of the following components are seen in a slide of human cheek cell when observed under a microscope?
  • a)
    Cell wall, cytoplasm, nucleus
  • b)
    Cell membrane, protoplasm, nucleus
  • c)
    Cell membrane, cytoplasm, nucleus
  • d)
    Cell wall, protoplasm, nucleus
Correct answer is option 'C'. Can you explain this answer?

Swati Verma answered
The cells do not have a cell wall. However, each cell has a thin cell membrane. A large vacuole is present at the center of each cell and is surrounded by the cytoplasm. A lightly stained cytoplasm is observed in each cell. A deeply stained nucleus is observed at the center of each cell.

Match the following with correct response:
  • a)
    1-B, 2-D, 3-A, 4-C
  • b)
    1-D, 2-A, 3-C, 4-B
  • c)
    1-C, 2-B, 3-D, 4-A
  • d)
    1-A, 2-C, 3-B, 4-D
Correct answer is option 'A'. Can you explain this answer?

Imk Pathshala answered
Cells are enclosed by a plasma membrane composed of proteins and lipids. It separates the contents of the cell from the external environment. It permits entry of selective substances in the cell. It allows exit of selective substances from the cell.
Tonoplast is the membrane which bounds the chief vacuole of a plant cell. It is also known as the vacuolar membrane. It separates the vacuolar contents from the cytoplasm of the cell.
Stroma is the ground material of chloroplast. It is the part of a tissue or an organ that has a connective and structural role.
Each of the partial partitions in a mitochondrion formed by infolding of the inner membrane is known as Cristae.

Read the text carefully and answer the questions:
Cell organelles are enclosed by membranes. Cell organelles are the endoplasmic reticulum, Golgi apparatus, lysosomes, mitochondria and plastids. The endoplasmic reticulum (ER) is a large network of membrane-bound tubes and sheets. It looks like long tubules or round or oblong bags. There are two types of ER rough endoplasmic reticulum (RER) and smooth endoplasmic reticulum (SER). RER looks rough under a microscope because it has particles called ribosomes attached to its surface. The ribosomes, which are present in all active cells, are the sites of protein manufacture. The Golgi apparatus, first described by Camillo Golgi, consists of a system of membrane-bound vesicles arranged approximately parallel to each other in stacks called cisterns.
Q. The cell organelle involved in forming complex sugars from simple sugars are:
  • a)
    golgi apparatus
  • b)
    ribosomes
  • c)
    endoplasmic reticulum
  • d)
    plastids
Correct answer is option 'A'. Can you explain this answer?

lavi kasana answered
Golgi appartus is correct answer

The extra stain from the slide if present is removed by:
  • a)
    keeping slide under running water
  • b)
    evaporation by heating
  • c)
    soaking with filter paper
  • d)
    drying stain under sunlight
Correct answer is option 'C'. Can you explain this answer?

Swati Verma answered
The staining of the peel must be appropriate. Excess stain can be removed by rinsing the peel with water taken in the watch glass. The extra stain from the slide if present is removed by soaking with filter paper. Filter paper absorbs the excess water and stain.

Assertion (A): When the displacement of a body is directly proportional to the square of the time. Then the body is moving with uniform acceleration.
Reason (R): The slope of velocity-time graph with time axis gives acceleration.
  • a)
    Both A and R are true and R is the correct explanation of A.
  • b)
    Both A and R are true but R is not the correct explanation of A.
  • c)
    A is true but R is false.
  • d)
    A is false but R is true.
Correct answer is option 'B'. Can you explain this answer?

Avinash Patel answered
Explanation:
To determine the correctness of the assertion and the reason, let's analyze each statement separately:



Assertion (A): When the displacement of a body is directly proportional to the square of the time. Then the body is moving with uniform acceleration.
This statement implies that the displacement-time relationship is given by:




s ∝ t^2


If displacement is directly proportional to the square of time, it means that the body is undergoing uniform acceleration. This is because the equation of motion for an object moving with uniform acceleration is given by:




s = ut + (1/2)at^2


Since the displacement is directly proportional to the square of time, the coefficient of t^2 is (1/2)a, which means the acceleration is constant. Therefore, assertion (A) is true.



Reason (R): The slope of velocity-time graph with time axis gives acceleration.
The slope of a velocity-time graph represents the rate of change of velocity with respect to time, which is acceleration. This is derived from the definition of acceleration as the rate of change of velocity:




a = Δv / Δt


The slope of the velocity-time graph is given by:




slope = (change in velocity) / (change in time)


Therefore, the reason (R) is true.



Conclusion:
From the analysis of both the assertion and the reason, we can conclude that:



Both A and R are true but R is not the correct explanation of A.
The reason (R) is true and provides additional evidence for the validity of the assertion (A), but it does not directly explain why the body is moving with uniform acceleration when the displacement is proportional to the square of time.

If two objects move in a circular path of radii in the ratio of 1:3 and take some time to complete the circle, what is the ratio of their speeds?
  • a)
    1:3
  • b)
    3:1
  • c)
    r2/r1
  • d)
    r1/r2
Correct answer is option 'A'. Can you explain this answer?

Swati Verma answered
Let the radius of circular path be r and 3r respectively.
Let the speed of first and second objects be v1 and v2 respectively.
The length of the first track = 2πr
Time is taken by the first object = 2πr/v1
The length of the second track = 2πr(3r) = 6 πr
Time is taken by the second object t = 6πr/v2
Time taken by both object are the same

Match the following with the correct response:
  • a)
    (a) - (i), (b) - (iii), (c) - (ii), (d) - (iv)
  • b)
    (a) - (iv), (b) - (i), (c) - (iii), (d) - (ii)
  • c)
    (a) - (iii), (b) - (ii), (c) - (iv), (d) - (i)
  • d)
    (a) - (ii), (b) - (iv), (c) - (i), (d) - (iii)
Correct answer is option 'B'. Can you explain this answer?

Aditi Sharma answered
  • In a prokaryotic cell, the nuclear region is poorly defined due to the absence of a nuclear membrane. Such an undefined nuclear region containing only nucleic acids is called a nucleoid,
  • On the other hand, organisms with cells having a nuclear membrane are called eukaryotes. Eukaryotic cells are considered complete cells.
  • Viruses are the link between the living and the non-living because they lack membranes and do not show any characteristics of life until they enter the body of a host,
  • Peroxisomes are small, membrane-enclosed organelles that contain enzymes involved in a variety of metabolic reactions. They help in the removal of toxic substances from the cell. They are surrounded by only a single membrane.

Internal forces are forces which bodies exert on each other when the bodies are part of the system is
  • a)
    false
  • b)
    partially false
  • c)
    partially true
  • d)
    true
Correct answer is option 'D'. Can you explain this answer?

Lavanya Menon answered
Internal forces are those forces which are exerted on each other when the bodies are part of the system. The forces acting between the atoms of molecules that keep them together are an example of internal force.

Assertion (A): Cell vomiting process occurs in cells to remove undigested substances, secrete hormones, enzymes, and transport various substances.
Reason (R): Cell vomiting is a process in which the waste materials from the cell are extruded through the plasma membrane by diffusing the vesicles containing materials needs to be taken out of the body.
  • a)
    Both A and R are true and R is the correct explanation of A.
  • b)
    Both A and R are true but R is not the correct explanation of A.
  • c)
    A is true but R is false.
  • d)
    A is false but R is true.
Correct answer is option 'A'. Can you explain this answer?

Meera Rana answered
Exocytosis or cell vomiting is a process in which the waste materials from the cell are extruded through the plasma membrane by diffusing the vesicles containing materials that need to be taken out of the body. This process occurs in cells to remove undigested substances, secrete hormones, enzymes, and transport various substances.

Read the text carefully and answer the questions:
Cell organelles are enclosed by membranes. Cell organelles are the endoplasmic reticulum, Golgi apparatus, lysosomes, mitochondria and plastids. The endoplasmic reticulum (ER) is a large network of membrane-bound tubes and sheets. It looks like long tubules or round or oblong bags. There are two types of ER rough endoplasmic reticulum (RER) and smooth endoplasmic reticulum (SER). RER looks rough under a microscope because it has particles called ribosomes attached to its surface. The ribosomes, which are present in all active cells, are the sites of protein manufacture. The Golgi apparatus, first described by Camillo Golgi, consists of a system of membrane-bound vesicles arranged approximately parallel to each other in stacks called cisterns.
Q. Which cell organelle plays a crucial role in detoxifying many poisons and drugs in a cell?
  • a)
    Vacuoles
  • b)
    Golgi apparatus
  • c)
    Lysosomes
  • d)
    Smooth endoplasmic reticulum
Correct answer is option 'D'. Can you explain this answer?

Divya Sriram answered
The Smooth Endoplasmic Reticulum (SER) plays a crucial role in detoxifying many poisons and drugs in the liver cells of vertebrates. So option D is correct.

When two substances A and B are powdered together in a pestle and mortar, a large amount of heat is evolved. As a result, a new substance C is formed. What is the nature of the new substance?
i. compound
ii. mixture
iii. element
  • a)
    Mixture
  • b)
    Compound
  • c)
    Element
  • d)
    Both compound and mixture
Correct answer is option 'B'. Can you explain this answer?

Swati Verma answered
A compound is a substance formed when two or more elements are chemically bonded together. The property of the compound has always different from its constituents. It has a fixed composition. The constituents of the compound can be separated by chemical or electrochemical reactions. During chemical reaction heat is evolved and a new substance is formed having new characters. Here, the reaction between substance A and substance B leads to form a new substance C. So a new substance is a compound.

The ratio of speed to the magnitude of velocity when the body is moving in one direction is
  • a)
    equal to one
  • b)
    greater than or equal to one
  • c)
    less than one
  • d)
    greater than one
Correct answer is option 'A'. Can you explain this answer?

Radha Iyer answered
Explanation:
When an object is moving in one direction, the speed and velocity of the object have the same magnitude but different directions. The ratio of speed to the magnitude of velocity can be calculated as follows:
1. Speed is defined as the distance traveled per unit of time, and it is a scalar quantity. It only takes into account the magnitude of the displacement.
2. Velocity, on the other hand, is defined as the rate of change of displacement over time, and it is a vector quantity. It takes into account both the magnitude and direction of displacement.
3. Since the object is moving in one direction, the magnitude of the velocity will be equal to the speed.
4. Therefore, the ratio of speed to the magnitude of velocity will be equal to 1, since the magnitudes are the same.
5. In other words, the speed and magnitude of velocity will have the same numerical value.
Answer: A. Equal to one

To observe starch granules in potato under a microscope, freshly cut surface of potato placed on a slide. The stain that will show starch granules clearly is:
  • a)
    safranin
  • b)
    iodine
  • c)
    eosin
  • d)
    methylene blue
Correct answer is option 'B'. Can you explain this answer?

Hansa Sharma answered
Place a slice of a potato on a paper towel at top of a paper plate and add a drop of the iodine solution to the potato slice. Note the color change. A change of color to blue-black or purple color suggests that starch is present. If there is no change in color, this suggests no starch is detectable.

A mixture of iron filings and sulphur is heated in a hard boiling tube. Which of the following will be observed?
  • a)
    Iron will melt first
  • b)
    Sulphur will melt first
  • c)
    The mixture becomes red hot without melting
  • d)
    Mixture sublimes
Correct answer is option 'B'. Can you explain this answer?

Aditi Sharma answered
When we start heating a mixture of iron filing and sulphur, the sulphur melts reacting exothermically (that is with the production of heat) with the iron filings to form the compound Iron (II) sulfide. The compound formed has properties that are different from both sulfur and iron. For instance, the compound does not have the magnetic properties of iron, and thus a magnet that could have easily separated iron nails and sulphur initially, will not be able to separate iron and sulphur from Iron (II) sulphide.

Newton's First Law of Motion is also called as:-
  • a)
    Law of Action & Reaction
  • b)
    Law of Momentum
  • c)
    None of these
  • d)
    Law of Inertia
Correct answer is option 'D'. Can you explain this answer?

Swati Verma answered
Newton's first law of motion is also referred to as the Law of Inertia. An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.

Which of the is true for displacement?
A. It cannot be zero.
B. Its magnitude is greater than the distance travelled by the object.
C. It’s the shortest distance between initial & final position.
D. It is a vector quantity.
  • a)
    A, B and C are correct
  • b)
    A and B are correct
  • c)
    All of these
  • d)
    C and D are correct
Correct answer is option 'D'. Can you explain this answer?

Swati Verma answered
  • When a body moves from one position to another, the shortest (straight line) distance between the initial position and final position of the body is known as its displacement. It's a vector quantity.
  • Displacement can be zero, less than the magnitude of distance but can never be more than the magnitude of distance covered.

Which of the following lacks nucleus?
  • a)
    WBC
  • b)
    Nerve cell
  • c)
    Muscle cell
  • d)
    RBC
Correct answer is option 'D'. Can you explain this answer?

Swati Verma answered
RBC is called as red blood corpuscles. Red Blood Cells in mammals anucleate when mature i.e. they do not contain a nucleus. This is so that the cell has maximum space for haemoglobin.

Match the following with the correct response:
  • a)
    (a) - (i), (b) - (iii),(c) (h), (c0 - (iv)
  • b)
    (a) - (ii), (b) - (iv),(c) - (i), (d) - (iii)
  • c)
    (a) - (iii), (b) - (ii).(c) - (iv), (d) - (i)
  • d)
    (a) - (iv), (b) - (i),(c) - (iii), (d) - (ii)
Correct answer is option 'D'. Can you explain this answer?

Swati Verma answered
i. Friction is the force that makes it difficult for one object to slide along the surface of another.
ii. The limiting friction is the frictional force just sufficient to move the object.
iii. Sliding friction refers to the resistance created by two objects sliding against each other.
iv. Rolling friction refers to the resistance created by an object rolling across a surface.

Read the text carefully and answer the questions:
A suspension is a heterogeneous mixture in which the solute particles do not dissolve but remain suspended throughout the bulk of the medium. Particles of a suspension are visible to the naked eye. The particles of a suspension scatter a beam of light passing through it and make its path visible. Due to the relatively smaller size of particles, as compared to that of a suspension, the mixture appears to be homogeneous. The scattering of a beam of light is called the Tyndall effect. The components of a colloidal solution are the dispersed phase and the dispersion medium. The solute-like component or the dispersed particles in a colloid form the dispersed phase, and the component in which the dispersed phase is suspended is known as the dispersing medium.
Q. Which of the following is not the property of colloid?
  • a)
    Colloids are big enough to scatter a beam of light passing through it.
  • b)
    A colloid is a heterogeneous mixture.
  • c)
    Size of particles of a colloid is too small
  • d)
    A colloid is very unstable
Correct answer is option 'D'. Can you explain this answer?

Let's Tute answered
  • Colloids are stable mixtures, unlike suspensions, which can separate over time.
  • They are heterogeneous at a microscopic level but appear homogeneous to the naked eye.
  • Colloid particles are small enough to remain suspended and do not settle down.
  • The particles are big enough to scatter light, showing the Tyndall effect.

Complete the sentence. Friction always ____________       
  • a)
    works in direction of motion       
  • b)
    opposes the direction of motion       
  • c)
    both of these       
  • d)
    none of these 
Correct answer is option 'B'. Can you explain this answer?

Imk Pathshala answered
- Friction always opposes the motion.
- Friction is a force that acts in the opposite direction to the movement of an object.
- It resists the relative motion between two surfaces in contact.
- This opposing force can slow down or stop objects in motion.
- While friction can be useful (e.g., providing traction for walking), its fundamental nature is to resist motion between surfaces.

Conversion of solid directly into its vapour form is called:
  • a)
    evaporation
  • b)
    vaporisation
  • c)
    distillation
  • d)
    sublimation
Correct answer is option 'D'. Can you explain this answer?

Swati Verma answered
Sublimation is the phase transition of a substance directly from the solid to the gas phase without passing through the intermediate liquid phase.

Branched involuntary muscles fibres are found in
  • a)
    ureters
  • b)
    limbs
  • c)
    heart
  • d)
    tongue
Correct answer is option 'C'. Can you explain this answer?

Swati Verma answered
Involuntary muscles are found in walls of hollow tubular organs like an alimentary canal, ducts of glands, urogenital ducts, and blood vessels except the heart. They show slow contractions but remain contracted for a long period of time.

Read the text carefully and answer the questions:
A suspension is a heterogeneous mixture in which the solute particles do not dissolve but remain suspended throughout the bulk of the medium. Particles of a suspension are visible to the naked eye. The particles of a suspension scatter a beam of light passing through it and make its path visible. Due to the relatively smaller size of particles, as compared to that of a suspension, the mixture appears to be homogeneous. The scattering of a beam of light is called the Tyndall effect. The components of a colloidal solution are the dispersed phase and the dispersion medium. The solute-like component or the dispersed particles in a colloid form the dispersed phase, and the component in which the dispersed phase is suspended is known as the dispersing medium.
Q. A mixture of sulphur and carbon disulphide is:
  • a)
    Homogeneous and does not show Tyndall effect
  • b)
    Heterogeneous and does not show Tyndall effect
  • c)
    Heterogeneous and shows Tyndall effect
  • d)
    Homogeneous and shows Tyndall effect
Correct answer is option 'A'. Can you explain this answer?

Imk Pathshala answered
  • A mixture of sulphur and carbon disulphide is homogeneous.
  • In a homogeneous mixture, the components are evenly distributed and appear as a single phase.
  • This mixture does not show the Tyndall effect because the particles are too small to scatter light.

 Which of the following options is a colloidal solution that exhibits the Tyndall effect?
  • a)
    Tinture iodine
  • b)
    Egg white 
  • c)
    Milk
  • d)
    Starch solution
Correct answer is option 'C'. Can you explain this answer?

Imk Pathshala answered
The Tyndall effect is observed when light is scattered by particles in a colloidal solution. It is not seen in true solutions.
  • Milk, egg white, and starch solution are examples of colloids. They can scatter light, showing the Tyndall effect. Among these, milk is a well-known colloidal solution that exhibits the Tyndall effect.
  • Tincture iodine is a true solution and does not exhibit this effect, as its particles are too small to scatter light.

Find the incorrect statement about Newton’s law of action and reaction. Action and reaction:
  • a)
    are equal in magnitude
  • b)
    act on the same bodies
  • c)
    act simultaneously
  • d)
    are different in direction
Correct answer is option 'B'. Can you explain this answer?

Swati Verma answered
Newton’s third law of motion explains action and reaction. Action and reaction act simultaneously, are equal in magnitude. They act in different directions and acts on different bodies.

Which of the following plant tissues do not possess living protoplasm at maturity?
  • a)
    Collenehyma
  • b)
    Trachea
  • c)
    Epidermis
  • d)
    Sclerenchyma
Correct answer is option 'D'. Can you explain this answer?

Aditi Sharma answered
Sclerenchyma is permanent tissue present in different parts of plants. They are thick-walled and do not possess living protoplasm at maturity because these are dead.

Chapter doubts & questions for Science - Sample Papers For Class 9 2025 is part of Class 9 exam preparation. The chapters have been prepared according to the Class 9 exam syllabus. The Chapter doubts & questions, notes, tests & MCQs are made for Class 9 2025 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests here.

Chapter doubts & questions of Science - Sample Papers For Class 9 in English & Hindi are available as part of Class 9 exam. Download more important topics, notes, lectures and mock test series for Class 9 Exam by signing up for free.

Sample Papers For Class 9

81 docs|11 tests

Top Courses Class 9

Signup to see your scores go up within 7 days!

Study with 1000+ FREE Docs, Videos & Tests
10M+ students study on EduRev
© EduRev
Education Revolution
Signup to see your scores go up within 7 days!
Access 1000+ FREE Docs, Videos and Tests
Takes less than 10 seconds to signup