SEE Science & Technoogy Question Paper 2080 - Sudurpaschim Province

Netizenship refers to the behavior, rights, and responsibilities of individuals as active participants in the online community. It encompasses the way people engage with digital content, communicate with others, and contribute to the internet, emphasizing respectful and responsible interaction. 

Blood pressure is defined as the force exerted by circulating blood on the walls of the blood vessels. It is written as a ratio of the systolic pressure over diastolic pressure, for example, 120/80 mm Hg.

Conservation of the one-horned rhinoceros is essential due to its endangered status. Key strategies include protecting natural habitats by safeguarding national parks and strengthening anti-poaching measures through increased patrolling and the use of technology like drones. Engaging local communities in conservation efforts and raising public awareness through educational programs can help foster support for protecting this species.

Additionally, translocation and captive breeding programs can enhance rhino populations and genetic diversity. Conducting research to monitor rhino health provides valuable data for effective conservation strategies. Enforcing strong legal frameworks and policies against poaching and habitat destruction is crucial. By implementing these measures, we can work towards ensuring the survival of the one-horned rhinoceros for future generations.

In the given chemical reaction, Manganese dioxide (\(\rm MnO_{2}\)) acts as a catalyst in the decomposition of potassium chlorate.

It increases the decomposition rate of Potassium chlorate.

Hence, it is a positive catalyst. 

Ammonia is a basic gas in nature.

Hence, red litmus paper changes into blue when it is inserted into the jar containing ammonia.

From the diagram, it is observed that light bends away from the normal when it passes from medium ‘A’ to medium ‘B’. Hence, Medium ‘A’ is denser and has higher refractive index than Medium ‘B’.

Since critical angle is angle of incidence in denser medium for which angle of refraction is a right angle, therefore, the critical angle is formed in Medium A before total internal reflection occurs.

The following are any two functions of a queen bee:

• It participates in the nuptial flight and lays eggs.
• It regulates the activities of the hive by secreting pheromones.

Any two natural processes that cause climate change are as follows:

1. Change in solar radiation: Almost all of the energy that affects the climate on the earth originates from the Sun. The energy output is not constant. It varies over time and this has an impact in our climate.
2. Drastic weather changes: Climate change can also occur through drastic weather changes. Disasters like hurricanes or flood can cause the significant damage to the surrounding environment, which, in turn, can affect the climate.

The frequency of Direct Current (DC) is zero.

Frequency refers to how many times the current or voltage alternates (or cycles) in a second. It is measured in Hertz (Hz), where 1 Hz equals one cycle per second.

DC is constant and unidirectional, meaning it doesn't alternate. Since frequency measures how often the direction or magnitude of current changes, and in DC there is no change, the frequency is zero.

1.Ans:

The chemical reaction is of the laboratory preparation of \(\rm CO_{2}\) gas.

Reaction:

When calcium carbonate is treated with dilute hydrochloric acid, carbon dioxide is formed.

\(\rm CaCO_{3} \) + \(\rm 2HCl \) → \(\rm CaCl_{2} \) +\(\rm H_{2}O \) + \(\rm CO_{2}\) ↑

2.Ans:

If the surface area of two or more reactants is large, there is great chance of collision course together and the reaction rate is increased.

Hence, he/she used powder of marble instead of marble chips as the reactants will have larger surface areas and the rate of reaction would be faster.

Gold is a noble metal, which means it is highly resistant to corrosion and oxidation. It does not react with most chemicals, including water and air. As a result, when the ring was lost in the field for two months, it was not subjected to any chemical reactions that could alter its mass or cause deterioration.

Additionally, gold is a dense and malleable metal that does not wear down easily. Even when buried in soil, it can withstand pressure and environmental factors without losing weight.

The fading luster of metallic heritage in the Kathmandu Valley is primarily caused by air pollution, particularly from vehicle emissions and industrial activities. The presence of pollutants, such as sulphur dioxide (\(\rm SO_{2}\)) and nitrogen oxides (NOx), can lead to the formation of acidic compounds that corrode metals, tarnishing their surface and deteriorating their appearance over time.

One chemical equation that illustrates the impact of air pollution on metallic surfaces is the reaction of sulfur dioxide with oxygen and water to form sulphuric acid.

\(\rm SO_{2}\) + \(\rm O_{2}\) + \(\rm H_{2}O\) → \(\rm H_{2}SO_{4}\)

\(\rm H_{2}SO_{4}\) further corrodes metals. For eg: When \(\rm H_{2}SO_{4}\) reacts with a metal, such as copper (Cu), it can lead to corrosion of the metal.

\(\rm Cu\) + \(\rm H_{2}SO_{4}\) → \(\rm CuSO_{4}\) + \(\rm H_{2}\)

In this reaction, the copper metal is corroded by the sulphuric acid, leading to the formation of copper sulphate, which can further contribute to the deterioration of metallic heritage.

1.  The molecular formula of X(ethanol) is : \(\rm C_{2}H_{5}OH\)

    2.The structural formula of the compound formed by the removal of one H and one -Oh                from the compound kept at X is:

(ethene is formed with water as a by product)

Detailed and minute observations revealed that atomic masses cannot be considered as the sole basis to classify elements into groups and periods as given by Mendeleev.

This led to development of Modern periodic law and modern periodic table.

The positive aspects of the modern periodic table relative to Mendeleev's periodic table are:

1. The wrong position of some elements like argon and potassium, cobalt and nickel due to atomic weights, has been solved by arranging the elements in the order of their increasing atomic number without changing their own places.
2. The isotopes of the same element have the same atomic numbers. Therefore, they find the same position in the modern periodic table.
3. It separates metals from non-metals as well as representative elements from transition elements.
4. The elements such as iron, cobalt and nickel of groups VIII of Mendeleev's periodic table are placed at 8th, 9th and 10th groups respectively. 

The transmission of digital signals involves sending information represented in binary format (0s and 1s) over a communication medium. Here’s how it typically works:

Encoding: The original information (such as voice, text, or video) is converted into a digital format through a process called encoding. This involves converting the analog signal into a series of binary numbers.

Modulation (if necessary): To effectively transmit digital signals over certain media (like radio waves), modulation techniques may be used. Modulation changes the properties of a carrier wave (such as its amplitude or frequency) to encode the digital information.

Transmission Medium: Digital signals can be transmitted over various mediums, including:

• Copper Cables: Twisted pair or coaxial cables are commonly used for telephone and cable TV services.
• Fiber Optic Cables: Light signals are transmitted through fiber optic cables, offering high-speed and long-distance communication.
• Wireless Channels: Digital signals can also be transmitted wirelessly through radio waves, as seen in Wi-Fi and mobile networks.

Receiving and Decoding: At the receiving end, the digital signal is detected, demodulated (if applicable), and decoded back into its original format for use by devices like computers, phones, or televisions.

Some of digital signal's applications are:

1. Watches: Digital and smart watches used digital signals.
2. Mobile Phones: All mobile phones process lots of digital signals. They process our speech digitally to remove background noise, echo, etc. They improve the quality of the images you click using digital image processing.

From the given diagram of blood, we can label A, B, C, and D as follows:

• A: Red Blood Cells
• B: White Blood Cells
• C: Platelets
• D: Plasma

Now, we can answer the questions as follows:

1. Plasma covers 55% part of the blood. It is a hay-colored fluid that constitutes around 55% of the total composition of the blood. The blood corpuscles are free to float on the plasma.
2. White Blood Cells is concerned with leukemia. Leukemia is a diseased condition of the human body in which the number of White Blood Cells increases above normal levels.
3. When the number of Red Blood Cells (A) decreases below the normal level, it results in anaemia.
4.  

1.Ans:

The transformer manufactured by the company has the following specifications:

Primary Coil Turns: 200 turns

Secondary Coil Turns: 100 turns

This transformer is a step-down transformer because it has more turns in the primary coil than in the secondary coil. This configuration reduces the voltage from the primary to the secondary.

2.Ans:

To find the secondary voltage when 50 V DC is applied to the primary coil, we can use the transformer voltage formula:

$\frac{ N_p}{N_s}$ = $\frac{ V_p}{V_s}$

Given:

Number of primary windings ( \(\rm N_p\) )= \(\rm 200\) 

Number of secondary coils ( \(\rm N_s\))=  \(\rm 100\) 

Primary Voltage( \(\rm V_p\) )=  \(\rm 50V\) 

Secondary Voltage( \(\rm V_s\) )= ?

$\frac{ N_p}{N_s}$ = $\frac{ V_p}{V_s}$

\(\rm or, \) $\frac{200}{100}$ = $\frac{ 50}{V_s}$

\(\rm or, \) $\frac{ 2}{1}$ = $\frac{50 }{V_s}$

\(\rm or, \) \(\rm V_s \)   = $\frac{50 }{2}$

\(\rm or, \) \(\rm V_s \)   = \(\rm 25 \) 

Thus, the secondary voltage will be 25 V.

3.Ans:

In an ideal transformer, the relation between input and output energy is given by the principle of conservation of energy. The power input to the primary coil equals the power output from the secondary coil, assuming no losses:

\(\rm P_{in}\)=\(\rm P_{out}\)

4.Ans:

Step-down transformers, like the one described, are commonly used in daily life for various applications, including:

• Charger Adapters: They are used in adapters for charging devices such as mobile phones and laptops by converting high voltage AC from wall outlets to lower voltage DC suitable for charging.
• Power Supplies: They provide lower voltages for household appliances and electronic devices that require a specific voltage level for safe operation.