10th Science - 2nd Mid Term Test 2024 Solutions
Tenkasi District | Standard 10
PART - I: Choose the correct answer
1) The minimum distance needed for an echo is ............
2) The frequency which is audible to the human ear is ............
3) The S.I unit of radioactivity is ............
4) ............ aprons are used to protect us from gamma radiations
5) Photolysis is a decomposition reaction caused by ............
6) Rectified spirit is an aqueous solution which contains about ............ of ethanol
7) The term Ethnobotany was coined by ............
8) The best way of direct dating fossils of recent origin is by ............
9) Pusa Komal is a disease resistant variety of ............
10) World 'No Tobacco Day' is observed on ............
PART - II: Answer any 7 questions (Q.No. 20 is compulsory)
11) Name three animals which can hear Ultrasonic Vibrations
- Bat
- Dolphin
- Dog
12) Explain why the ceilings of concert halls are curved?
13) Arrange in descending order on the basis of their penetration power Alpha rays, Beta rays, Gamma rays, Cosmic rays.
- Cosmic rays
- Gamma rays (γ)
- Beta rays (β)
- Alpha rays (α)
14) Say true or false
i) Silver metal can displace hydrogen gas from nitric acid.
False. Silver is less reactive than hydrogen and lies below it in the electrochemical series, so it cannot displace hydrogen from acids.
ii) The normal pH of human blood is 6.4
False. The normal pH of human blood is slightly alkaline, ranging from 7.35 to 7.45.
15) Name the simplest ketone and give its structural formula
Name: The simplest ketone is Propanone, commonly known as Acetone.
Molecular Formula: $CH_3COCH_3$
Structural Formula:
H O H
| || |
H-C--C--C-H
| |
H H
16) Why is Archaeopteryx considered to be a connecting link?
- Reptilian features: It had teeth in its jaws, claws on its wings, and a long, bony tail.
- Avian (bird) features: It had feathers and wings, similar to modern birds.
17) Define genetic engineering
18) Expand (i) HIV (ii) BMI
(i) HIV: Human Immunodeficiency Virus
(ii) BMI: Body Mass Index
19) How are e-wastes generated?
20) If the pH of a solution is 4.5. What is its pOH?
We know that for any aqueous solution at 25°C:
$pH + pOH = 14$
Given, $pH = 4.5$
$pOH = 14 - pH$
$pOH = 14 - 4.5$
$pOH = 9.5$
Therefore, the pOH of the solution is 9.5.
PART - III: Answer any 3 questions (Q.No. 25 is compulsory)
21) a) What is the audible range of frequency
b) Mention two cases in which there is no Doppler effect in sound.
a) Audible range of frequency:
The range of frequencies that can be heard by a normal human ear is from 20 Hz to 20,000 Hz (or 20 kHz). This range is known as the audible range.
b) Cases with no Doppler effect:
There is no Doppler effect under the following conditions:
- When both the source of sound and the listener are at rest.
- When the source and the listener move in such a way that the distance between them remains constant (e.g., moving in concentric circles).
22) Differentiate reversible and irreversible reactions.
| Feature | Reversible Reactions | Irreversible Reactions |
|---|---|---|
| Direction | Can proceed in both forward and backward directions. | Can proceed only in the forward direction. |
| Equilibrium | Can attain a state of chemical equilibrium. | Cannot attain equilibrium. |
| Completion | These reactions never go to completion. | These reactions proceed to completion. |
| Products | Products can react to form the original reactants. | Products cannot be converted back to reactants under the same conditions. |
23) State the applications of DNA finger printing technique.
- Forensic Science: To identify criminals in crime investigations by matching DNA samples (from blood, hair, etc.) found at the crime scene.
- Paternity and Maternity Disputes: To determine the biological parents of a child.
- Identification of Victims: To identify victims of disasters like earthquakes, floods, or accidents when bodies are unrecognizable.
- Medical Diagnosis: To identify and diagnose inherited genetic disorders.
- Conservation of Wildlife: To study genetic diversity and track endangered species.
24) How can you determine the age of the fossils?
- Radiocarbon Dating (Carbon-14 Dating): This method is used to determine the age of fossils of recent origin (up to about 60,000 years old). It measures the ratio of the radioactive isotope Carbon-14 to the stable isotope Carbon-12. Living organisms maintain a constant ratio, but after death, Carbon-14 decays without being replaced. By measuring the remaining Carbon-14, the age of the fossil can be calculated.
- Uranium-Lead Dating: This method is used for dating very old rocks and the fossils contained within them. It is based on the radioactive decay of Uranium-238 to Lead-206. By measuring the ratio of uranium to lead in a rock sample, scientists can determine its age.
25) If A is a radioactive element which emits alpha particle and produces $_{104}Rf^{259}$, Write the atomic number and mass number of the element A.
An alpha particle is a helium nucleus, represented as $^4_2He$.
Let the radioactive element be A with mass number 'M' and atomic number 'Z', represented as $^M_ZA$.
The nuclear reaction can be written as:
According to the law of conservation of mass number and atomic number:
1. Conserving Mass Number (M):
$$ M = 259 + 4 $$ $$ M = 263 $$2. Conserving Atomic Number (Z):
$$ Z = 104 + 2 $$ $$ Z = 106 $$Thus, for the element A:
- Atomic Number = 106
- Mass Number = 263
PART - IV: Answer all the questions
26) a) Compare the properties of alpha, beta and gamma radiations.
| Property | Alpha (α) Rays | Beta (β) Rays | Gamma (γ) Rays |
|---|---|---|---|
| Nature | Helium nucleus ($^4_2He$) | Electron ($^{-1}_0e$) | 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 thin aluminium) | Very high (stopped by thick lead) |
| Speed | 1/10 to 1/20 times the speed of light | Up to 9/10 times the speed of light | Travels at the speed of light |
| Effect of E/M Field | Deflected towards negative plate | Deflected towards positive plate | Not deflected |
(OR)
b) The molecular formula of an alcohol is $C_4H_{10}O$. The locant number of its -OH group is 2.
i) Draw its structural formula
ii) Give its IUPAC name
iii) Is it saturated or unsaturated
i) Structural Formula:
The molecular formula is $C_4H_{10}O$. The -OH group is on the 2nd carbon atom.
H H H H
| | | |
H-C - C - C - C-H
| | | |
H OH H H
This can also be written as: $CH_3-CH(OH)-CH_2-CH_3$
ii) IUPAC Name:
The longest carbon chain has 4 carbon atoms (but-). It is an alcohol (-ol). The -OH group is on the 2nd carbon. Therefore, the IUPAC name is Butan-2-ol.
iii) Is it saturated or unsaturated:
The compound is saturated because all the carbon-carbon bonds in the chain are single bonds.
27) a) i) Differentiate between outbreeding and inbreeding?
ii) What are transgenic organisms?
i) Differentiation between Outbreeding and Inbreeding:
| Feature | Inbreeding | Outbreeding |
|---|---|---|
| Definition | Mating of closely related individuals within the same breed for 4-6 generations. | Mating of unrelated animals. It can be between individuals of the same breed (but no common ancestors) or between different breeds or species. |
| Genetic Variation | Decreases genetic variation and increases homozygosity. | Increases genetic variation and introduces new genes. |
| Advantage | Helps in accumulating superior genes and eliminating undesirable genes. Develops pure lines. | Produces offspring with desirable qualities of both parents (hybrid vigour). Helps overcome inbreeding depression. |
| Disadvantage | Continued inbreeding can lead to reduced fertility and productivity, known as inbreeding depression. | Can be complex and may not always produce the desired combination of traits. |
ii) Transgenic Organisms:
Transgenic organisms (also called Genetically Modified Organisms or GMOs) are plants, animals, or microorganisms whose DNA has been altered using genetic engineering techniques. This usually involves inserting a gene from a different species into the organism's genome to give it a new, desirable trait. For example, Bt-cotton is a transgenic plant that produces its own insecticide.
(OR)
b) i) What is metastasis?
ii) Suggest measures to overcome the problems of an alcoholic
i) What is metastasis?
Metastasis is the process by which cancer cells break away from the original (primary) tumor, travel through the blood or lymph system, and form new tumors (metastatic tumors) in other parts of the body. It is the primary cause of death from cancer.
ii) Measures to overcome the problems of an alcoholic:
- Education and Counselling: Providing proper education about the harmful effects of alcohol and counselling can help individuals avoid and overcome alcoholism.
- Medical Assistance: Seeking help from physicians for detoxification and to manage withdrawal symptoms. Medications can be prescribed to reduce cravings.
- Rehabilitation Centres: Admitting the individual to de-addiction and rehabilitation centres that provide a supportive environment for recovery.
- Support Groups: Joining support groups like Alcoholics Anonymous (AA) where individuals can share experiences and encourage each other to stay sober.
- Parental and Peer Support: Strong support from family and friends is crucial for the individual's motivation and recovery process.