10th Science Second Midterm Exam 2024: Solved Paper
Question Paper
Solutions
PART I: Choose the best answer (10 x 1 = 10)
1. The frequency, which is audible to the human ear is
2. Gamma radiations are dangerous because
3. In the nuclear reaction \( _6X^{12} \xrightarrow{\alpha \text{ decay }} _Z Y^A \), the value of A & Z.
4. Reaction between carbon and oxygen is represented by C(s) + O₂(g) → CO₂(g) + Heat. In which of the type(s), the above reaction can be classified?
(i) Combination Reaction (ii) Combustion Reaction (iii) Decomposition Reaction (iv) Irreversible Reaction
5. TFM in soaps represents __________ content in soap
6. The 'use and disuse theory' was proposed by
7. Organisms with modified endogenous gene or a foreign gene are also known as
8. Which type of cancer affects lymph nodes and spleen?
9. A renewable source of energy is
10. Green house effect refers to
PART II: Write any 5 questions (question no 18th is compulsory) (5 x 2 = 10)
11. Why does sound travel faster on a rainy day than on a dry day?
Sound travels faster on a rainy day because the humidity in the air is higher. Humid air is less dense than dry air because water molecules (H₂O, molecular mass ≈ 18) are lighter than the average molecules in dry air (mostly Nitrogen, N₂, mass ≈ 28 and Oxygen, O₂, mass ≈ 32).
Since the speed of sound is inversely proportional to the square root of the density of the medium, sound travels faster in less dense (humid) air.
12. Define one Roentgen.
One Roentgen (R) is defined as the quantity of radioactive substance which produces a charge of \(2.58 \times 10^{-4}\) coulomb in 1 kg of air under standard conditions of pressure and temperature.
13. Differentiate soaps and detergents.
| Feature | Soaps | Detergents |
|---|---|---|
| Source | They are prepared from natural vegetable oils and animal fats. | They are synthetic, prepared from hydrocarbons of petroleum. |
| Action in Hard Water | Form scum or precipitate in hard water, reducing cleaning efficiency. | Work effectively even in hard water as their calcium and magnesium salts are soluble. |
| Biodegradability | They are biodegradable. | Most detergents are non-biodegradable and can cause water pollution. |
14. Why is Archaeopteryx considered to be a connecting link?
Archaeopteryx is considered a connecting link between reptiles and birds because it possesses features of both groups:
- Reptilian characters: Long tail with free caudal vertebrae, claws on fingers, and teeth in its jaws.
- Avian (bird) characters: Presence of feathers on the body, forelimbs modified into wings, and a V-shaped furcula (wishbone).
15. State the applications of DNA fingerprinting technique.
Two major applications of DNA fingerprinting are:
- Forensic Science: It is used to identify criminals in cases of rape, murder, and other crimes by matching the DNA sample from the crime scene with that of the suspects.
- Paternity Testing: It is used to determine the biological father of a child in disputed parentage cases.
16. What are psychotropic drugs?
Psychotropic drugs are chemical substances that affect the brain and nervous system, altering mood, thoughts, perception, and behaviour. They are often used to treat mental health disorders but can also be misused. Examples include sedatives, stimulants, and hallucinogens.
17. What is the environmental effect caused by sewage?
Untreated sewage released into water bodies causes severe environmental effects:
- Water Pollution: It contaminates water sources, making them unfit for drinking and other uses.
- Eutrophication: The high nutrient content in sewage leads to excessive growth of algae (algal bloom), which depletes oxygen in the water, killing aquatic life.
- Spread of Diseases: Sewage contains harmful pathogens that can cause water-borne diseases like cholera, typhoid, and dysentery.
18. Calculate the amount of energy released when a radioactive substance undergoes fusion and results in a mass defect of 2 kg.
According to Einstein's mass-energy equivalence principle, the energy released (E) is related to the mass defect (m) by the equation:
\[ E = mc^2 \]
Given:
- Mass defect (m) = 2 kg
- Speed of light (c) = \(3 \times 10^8\) m/s
Calculation:
\[ E = 2 \times (3 \times 10^8)^2 \]
\[ E = 2 \times 9 \times 10^{16} \]
\[ E = 18 \times 10^{16} \text{ Joules} \]
Therefore, the amount of energy released is \(1.8 \times 10^{17}\) J.
PART III: Write any four questions (25th question is compulsory) (4 x 4 = 16)
19. Compare any four properties of alpha, beta and gamma radiations
| Property | Alpha (α) Rays | Beta (β) Rays | Gamma (γ) Rays |
|---|---|---|---|
| Nature | Helium nucleus (\( _2He^4 \)) | Electron (\( _{-1}e^0 \)) | Electromagnetic waves |
| Charge | Positive charge (+2e) | Negative charge (-1e) | No charge (neutral) |
| Ionising Power | Very high (100 times β, 10000 times γ) | Moderate | Very low |
| Penetrating Power | Very low (stopped by paper) | Moderate (stopped by aluminium foil) | Very high (stopped by thick lead) |
20. What is a chemical equilibrium? What are its characteristics?
Chemical Equilibrium: It is a state in a reversible chemical reaction where the rate of the forward reaction is equal to the rate of the reverse reaction. At this point, the concentrations of reactants and products remain constant over time.
Characteristics of Chemical Equilibrium:
- Dynamic Nature: Equilibrium is dynamic, meaning both forward and reverse reactions are still occurring, but at the same rate.
- Constant Concentrations: The concentrations of all reactants and products become constant.
- Closed System: Equilibrium can only be achieved in a closed system where no substances can enter or leave.
- Attainable from Either Direction: Equilibrium can be reached starting with either reactants or products.
21. Define Ethno botany and write its importance.
Ethnobotany: It is the scientific study of the traditional knowledge and customs of a people concerning plants and their medical, religious, and other uses.
Importance of Ethnobotany:
- Discovery of New Medicines: It provides valuable clues for the discovery of new drugs from plants based on traditional remedies.
- Conservation: It helps in the conservation of traditional plant species and the ecosystems they inhabit.
- Agricultural Insights: It provides information about traditional farming practices and resilient crop varieties.
- Cultural Preservation: It helps in documenting and preserving the cultural heritage and indigenous knowledge of communities.
22. Discuss the importance of biotechnology in the field of medicine.
Biotechnology has revolutionized medicine in several ways:
- Pharmaceuticals: Genetically engineered bacteria are used to produce vital substances like human insulin for diabetics, human growth hormone, and interferons.
- Vaccines: It has enabled the development of safer and more effective recombinant vaccines (e.g., Hepatitis B vaccine).
- Gene Therapy: It offers a way to correct genetic disorders by replacing a defective gene with a healthy one.
- Diagnostics: Techniques like PCR (Polymerase Chain Reaction) and ELISA are used for the rapid and accurate diagnosis of diseases like AIDS and COVID-19.
- Monoclonal Antibodies: These are used for targeted drug delivery to cancer cells and in diagnostic kits.
23. a) How is a cancer cell different from a normal cell? b) Differentiate between Type-1 and Type-2 diabetes mellitus.
a) Differences between a Cancer Cell and a Normal Cell:
- Uncontrolled Division: Cancer cells divide endlessly and uncontrollably, unlike normal cells which have a controlled cell cycle.
- Loss of Contact Inhibition: Cancer cells lose the property of contact inhibition, causing them to pile up and form tumors. Normal cells stop dividing when they come into contact with other cells.
- Metastasis: Cancer cells can spread from the original tumor to other parts of the body through blood or lymph, a property normal cells do not have.
- Undifferentiated: Cancer cells are often undifferentiated and do not perform the specialized functions of the parent tissue.
b) Difference between Type-1 and Type-2 Diabetes:
| Feature | Type-1 Diabetes | Type-2 Diabetes |
|---|---|---|
| Cause | The body's immune system destroys insulin-producing beta cells in the pancreas. | The body either doesn't produce enough insulin or the cells become resistant to insulin's effects. |
| Age of Onset | Usually diagnosed in children and young adults (Insulin-Dependent). | Most often diagnosed in adults, but increasingly seen in children (Non-Insulin-Dependent). |
| Treatment | Requires insulin injections. | Managed with lifestyle changes, oral medications, and sometimes insulin. |
24. How do rainwater harvesting structures recharge ground water?
Rainwater harvesting structures are designed to collect and store rainwater, allowing it to percolate deep into the ground to recharge groundwater aquifers. This is achieved through various methods:
- Percolation Pits/Recharge Pits: These are pits filled with gravel and sand. Rainwater collected from rooftops or open areas is diverted into these pits, from where it slowly seeps into the ground.
- Recharge Trenches: These are similar to pits but are trench-shaped, providing a larger surface area for water percolation.
- Injection Wells: Rainwater is channeled into defunct borewells or specially constructed wells, directly injecting water into deeper aquifers.
By preventing runoff and promoting infiltration, these structures help raise the water table and ensure water availability during dry seasons.
25. a) Calculate the pH of 0.001 molar solution of HCl. b) The hydroxide ion concentration of a solution is \(1 \times 10^{-11}\) M. What is the pH of the solution?
a) pH of 0.001 M HCl solution:
HCl is a strong acid, so it completely dissociates in water. \[ \text{HCl} \rightarrow H^+ + Cl^- \]
The concentration of H⁺ ions will be equal to the concentration of HCl.
\[ [H^+] = 0.001 \text{ M} = 10^{-3} \text{ M} \]
pH is calculated as: \[ \text{pH} = -\log[H^+] \]
\[ \text{pH} = -\log(10^{-3}) = 3 \]
The pH of the solution is 3.
b) pH from hydroxide ion concentration:
Given hydroxide ion concentration: \[ [OH^-] = 1 \times 10^{-11} \text{ M} \]
First, calculate the pOH: \[ \text{pOH} = -\log[OH^-] \]
\[ \text{pOH} = -\log(1 \times 10^{-11}) = 11 \]
We know that at 25°C: \[ \text{pH} + \text{pOH} = 14 \]
\[ \text{pH} = 14 - \text{pOH} \]
\[ \text{pH} = 14 - 11 = 3 \]
The pH of the solution is 3.
PART IV: Write all the questions (7 x 2 = 14, but marking seems inconsistent with the number of questions, solving all)
26. a) What do you understand by the term 'ultrasonic vibration'? b) State three uses of ultrasonic vibrations. c) Name three animals which can hear ultrasonic vibrations.
a) Ultrasonic Vibration: These are sound vibrations with frequencies higher than the upper limit of human hearing, which is approximately 20,000 Hertz (20 kHz).
b) Three Uses of Ultrasonic Vibrations:
- Medical Imaging: Used in ultrasonography to create images of internal body organs, fetuses, etc.
- SONAR: Used in ships and submarines for underwater navigation and to detect objects (Sound Navigation And Ranging).
- Industrial Cleaning: Used for cleaning delicate electronic parts, jewelry, and surgical instruments by dislodging dirt particles.
c) Three Animals that can Hear Ultrasonic Vibrations:
- Bats
- Dolphins
- Dogs
27. Give the balanced chemical equation of the following reactions: (i) Neutralization of NaOH with ethanoic acid. (ii) Evolution of carbon dioxide by the action of ethanoic acid with NaHCO₃. (iii) Oxidation of ethanol by acidified potassium dichromate. (iv) Combustion of ethanol.
(i) Neutralization of NaOH with ethanoic acid:
\[ \underset{\text{(Sodium hydroxide)}}{NaOH} + \underset{\text{(Ethanoic acid)}}{CH_3COOH} \rightarrow \underset{\text{(Sodium ethanoate)}}{CH_3COONa} + \underset{\text{(Water)}}{H_2O} \]
(ii) Evolution of carbon dioxide by the action of ethanoic acid with NaHCO₃:
\[ \underset{\text{(Ethanoic acid)}}{CH_3COOH} + \underset{\text{(Sodium bicarbonate)}}{NaHCO_3} \rightarrow \underset{\text{(Sodium ethanoate)}}{CH_3COONa} + \underset{\text{(Water)}}{H_2O} + \underset{\text{(Carbon dioxide)}}{CO_2} \uparrow \]
(iii) Oxidation of ethanol by acidified potassium dichromate:
\[ \underset{\text{(Ethanol)}}{CH_3CH_2OH} \xrightarrow[K_2Cr_2O_7 / H^+]{\text{[O]}} \underset{\text{(Ethanoic acid)}}{CH_3COOH} + H_2O \]
(iv) Combustion of ethanol:
\[ \underset{\text{(Ethanol)}}{C_2H_5OH} + \underset{\text{(Oxygen)}}{3O_2} \rightarrow \underset{\text{(Carbon dioxide)}}{2CO_2} + \underset{\text{(Water)}}{3H_2O} + \text{Heat} \]
28. a) Natural selection is a driving force for evolution-How? b) Differentiate between out breeding and inbreeding.
a) Natural Selection as a Driving Force for Evolution:
Natural selection is the process by which organisms with traits better suited to their environment tend to survive and reproduce more successfully. This differential survival and reproduction lead to a gradual change in the genetic makeup of a population over generations.
- Variation: Individuals within a population show variations in their traits.
- Struggle for Existence: Organisms produce more offspring than can survive, leading to competition for resources.
- Survival of the Fittest: Individuals with advantageous variations (adaptations) have a higher chance of surviving and reproducing.
- Inheritance: These advantageous traits are passed on to the next generation.
Over time, this process results in the accumulation of favourable traits, leading to the formation of new species, thus driving evolution.
b) Difference between Outbreeding and Inbreeding:
| Feature | Inbreeding | Outbreeding |
|---|---|---|
| Definition | Mating of closely related individuals within the same breed for 4-6 generations. | Mating of unrelated individuals. It can be between individuals of the same breed (but no common ancestors) or different breeds. |
| Purpose | To increase homozygosity and develop pure lines (e.g., to preserve desirable traits). | To increase genetic variation, produce hybrids with superior qualities (hybrid vigour), and overcome inbreeding depression. |
| Consequence | Can lead to inbreeding depression (reduced fertility and productivity) and increased chances of expressing harmful recessive traits. | Often results in offspring with enhanced fitness, growth, and productivity (heterosis). |
(OR)
29. a) Suggest measures to overcome the problems of an alcoholic. b) What are the consequences of deforestation?
a) Measures to Overcome Alcoholism:
- Medical Assistance: Detoxification under medical supervision to manage withdrawal symptoms safely.
- Counselling and Therapy: Psychological support through individual or group therapy to address the root causes of addiction.
- Support Groups: Joining support groups like Alcoholics Anonymous (AA) provides a community of peers for encouragement and accountability.
- Education and Awareness: Educating the individual and their family about the effects of alcoholism and the process of recovery.
- Rehabilitation Centers: Enrolling in a de-addiction and rehabilitation program offers a structured environment for recovery.
b) Consequences of Deforestation:
- Climate Change: Trees absorb carbon dioxide, a major greenhouse gas. Deforestation contributes to increased CO₂ levels and global warming.
- Soil Erosion: Tree roots hold the soil together. Their removal leads to soil erosion by wind and water, reducing soil fertility and causing landslides.
- Loss of Biodiversity: Forests are home to a vast number of species. Destroying them leads to habitat loss and extinction of plants and animals.
- Disruption of Water Cycle: Forests play a crucial role in the water cycle through transpiration. Deforestation can lead to reduced rainfall and desertification.
- Flooding: Forests act as natural sponges, absorbing rainwater. Their absence increases surface runoff, leading to more frequent and severe floods.