SEE EXAMINATION PAPER SOLVED OF SCIENCE PART 2

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(Group 'A')

1. Write short answer of the following questions.

a. What is the free fall?

= Free fall is the act of falling through the air with no outside forces acting upon the object, such as a parachute or wings. It is the natural motion of objects when they are only subject to the force of gravity. This motion is seen in things like skydiving, bungee jumping, and falling from high places.

b. State the law of floatation.

= The law of floatation states that any object, wholly or partially submerged in a fluid, is buoyed up by a force equal to the weight of the fluid displaced by the object.

c. Define heat energy in term of kinetic energy of molecules.

= Heat energy is the kinetic energy of molecules in a substance, which is the energy of their random motion. This energy can be transferred from one substance to another through conduction, convection, or radiation.

d. Where should be object kept infront of convex lens to get magnification 1?

= The object should be placed at the focal point of the convex lens, which is one focal length away from the lens.

e. Write the name of high quality coal?

= Anthracite Coal

f. Define promotor.

= A promotor is a person or business that helps to increase awareness, visibility, and sales of a product or service. This can be done through a variety of activities such as advertising, public relations, and other marketing efforts. Promotors also provide customer service, feedback and product knowledge to help drive sales.

g. What is an alkali?

= An alkali is a type of base containing an alkaline, or basic, pH that neutralizes acids. It can be found in a variety of forms, including soaps, detergents, and household cleaners.

h. Write two ores of silver?

= 1. Silverware 

2. Silver jewelry

i. Write two examples of thermosetting plastic?

= 1. Epoxy resin

2. Polyurethane

j. Write the main function of insulin hormone?

= The main function of insulin is to regulate blood glucose levels by facilitating the uptake of glucose from the bloodstream into cells, where it can be used to produce energy. It also has a role in the storage of glucose in the form of glycogen, and in lipid metabolism.

k. What is blood pressure?

= Blood pressure is the pressure of the blood against the walls of the arteries as it is pumped around the body by the heart. It is normally measured in units of millimeters of mercury (mmHg) and is made up of two different readings – the systolic pressure and the diastolic pressure. The systolic pressure is the higher of the two readings and represents the pressure when the heart is beating, while the diastolic pressure is the lower of the two and represents the pressure when the heart is at rest.

l. Write any two effects seen from klinefelter's disorder?

= 1. Infertility – Klinefelter's syndrome can cause infertility in men due to abnormal sperm production.

2. Delayed Puberty – Men with Klinefelter's syndrome may experience delayed puberty or incomplete sexual development.

m. Write the name of upper part and lower part used in grafting.

= Upper part: Scion

Lower part: Rootstock

n. Define monohybrid cross.

= A monohybrid cross is a type of genetic experiment that involves the crossing of two organisms that differ in a single trait, such as flower color or seed shape. This type of mating experiment is used to study patterns of inheritance, to determine the probability of certain traits appearing in offspring, and to better understand the role of dominant and recessive genes.

o. What is fossil?

= Fossils are the remains or traces of organisms from the past that are preserved in the Earth's crust. They provide evidence of past life forms, as well as information about the environment in which they lived. Fossils can include bones, shells, footprints, and even chemical compounds in ancient rocks.

(Group 'B')

2. What happens to ballon filled with air, when it goes very high altitude from surface of earth? Why?

= When a balloon filled with air goes very high into the atmosphere, the air inside the balloon contracts due to the decrease in air pressure. This causes the balloon to shrink, and eventually, the balloon will burst due to the lack of air pressure.

3. Gobar gas is more beneficial in rural area in Nepal? Give two reason.

=  1.Gobar gas is a cost-effective energy source in rural Nepal: Since it is produced from waste, it is very affordable compared to other energy sources, especially in areas where electricity is not easily accessible. 

2.Gobar gas is an eco-friendly energy source: It produces fewer emissions than other energy sources, making it an environmentally-friendly option for rural Nepal. Moreover, it helps to reduce the amount of waste in the environment by utilizing it for energy production.

4. Nowadays clinical thermometer is replaced by digital thermometer. Why?

= Digital thermometers are becoming increasingly popular over clinical thermometers due to their more accurate readings, shorter wait times, and ease of use. Digital thermometers are able to provide more accurate readings than clinical thermometers due to their increased sensitivity and faster processing speeds. Additionally, digital thermometers are able to provide near-instantaneous readings, whereas clinical thermometers can take up to several minutes to produce a reading. Finally, digital thermometers are much easier to use than clinical thermometers, as they often require only a single button press to activate and take a reading.

5. Write any two reasons for using nichrome as a heating element.

= 1. Nichrome is a durable metal alloy that is capable of withstanding extreme temperatures and does not corrode or degrade over time. This makes it an ideal choice for applications that require long-term heating.

2. Nichrome has a high electrical resistance, which allows it to heat up quickly and efficiently when a current is applied. This makes it an efficient choice for heating elements in many electrical appliances.

6. Write a chemical reaction between calcium and sulphuric acid. Mention the type of chemical reaction.

= Calcium + Sulphuric Acid → Calcium Sulphate + Hydrogen Gas

Type of Reaction: Single Displacement Reaction

7. Write down any two difference between PVC and Bakelite.

= 1. PVC is a thermoplastic material while Bakelite is a thermosetting material.

2. PVC can be easily molded into different shapes when heated, while Bakelite is difficult to process and is not heat resistant.

8. Though hydrochloric acid is formed inside our body, it is not called organic acid. Why?

= Hydrochloric acid is classified as an inorganic acid because it does not contain a carbon atom. Organic acids, on the other hand, are compounds that contain a carbon atom, as well as other elements, such as hydrogen, oxygen, nitrogen, and sulfur.

9. In general, iron is not used to make body parts of aeroplane. Why? Give any two reasons.

= 1. Iron is not as strong as aluminum, so it would not be able to withstand the high pressures and stresses that an airplane's body must endure.

2. Iron is heavier than aluminum, so using it to make body parts of an airplane would add unnecessary and excessive weight to the aircraft, reducing its fuel efficiency.

10. Write any two reasons that silk worm is useful insect.

= 1. Silk Worms provide us with a natural and high quality silk fabric, which is used for making clothing, furniture, décor items and accessories.

2. Silk Worms are also beneficial to the environment as they help with pest control by consuming aphids and other pests that can damage crops.

11. A cell of girl contain only 45, XO chromosomes, which type of chromosomes disorder is present in her body? Write any one symptoms of it.

= Turner Syndrome is the chromosome disorder present in the girl's body. Common symptoms of Turner Syndrome include short stature, infertility, and lack of sexual development.

12. Write any two difference between binary fission in amoeba and budding in yeast.

= 1. Binary Fission in Amoeba results in two daughter cells of equal size, while Budding in Yeast results in an unequal sized parent and daughter cell.

2. Binary Fission in Amoeba involves the splitting of the cell into two daughter cells, while Budding in Yeast involves the formation of a daughter cell from a protrusion of the parent cell.

13. Offsprings obtained from same parents show some similarities but they are not exactly similar to each other. Why? Write with reason.

= Offsprings obtained from the same parents show some similarities because they share roughly half of their genetic material from each parent. However, they are not exactly the same because of the influence of environmental factors that can affect the expression of their genes. Additionally, even within the same gene, different alleles can be expressed and passed down to the offspring, creating further variation in the individual.

14. Write any two applicatons of artificial satellites.

= 1. Remote Sensing: Artificial satellites are equipped with cameras, infrared detectors, and other instruments that allow it to capture images, measure temperatures, and collect environmental data from Earth. This information is used for a wide range of applications including weather forecasting, crop monitoring, land use mapping, and disaster management. 

2. Communications: Artificial satellites are used to transmit television signals and enable global communication via telephone, radio, and internet. They also provide a platform for global positioning systems (GPS) that allows ships and aircraft to navigate accurately.

 ( Group 'C')

15. A stone dropped freely from 72 m  height of the tower and reaches the ground in 6 seconds. Calculate acceleration due to gravity of that stone. At what condition does the acceleration due to gravity becomes zero?

= The acceleration due to gravity of the stone is g = (72 m)/(6 s2) = 12 m/s2. 

The acceleration due to gravity becomes zero when the stone is being lifted up with a constant velocity.

16. If a heater with power 2000W runs one hours, it gives 4.2x10^3 J heat. What will be the temperature increased in 20 kg of water with temperature 40°C by the heat?

= The temperature increase of the water will depend on a variety of factors, such as the size and shape of the container, the amount of insulation, etc. It is not possible to calculate the temperature increase without knowing these additional factors.

17. Which compound is represented by general formula CnH2n + 1OH? If value of n is 2 in this formula which compound is formed? Write it structural formula. If OH of this compound is replaced by H which compound is formed? Write its name and modular formula.

= The compound represented by the general formula CnH2n + 1OH with n = 2 is 2-Propanol, also known as Isopropyl Alcohol. Its structural formula is CH3CH(OH)CH3.

If the OH of this compound is replaced by H, the compound formed is 2-Propane, also known as Isopropane. Its molecular formula is C3H8.

18. Write any three application of forest in our daily life.

= 1. Forests provide a source of energy, food, and shelter for both humans and animals. Forests are a crucial source of food, fuel and raw materials for many communities around the world. 

2. Forests play a critical role in water regulation, purification and conservation. They act as natural filters, absorbing pollutants and stabilizing stream flow and groundwater levels, while also preventing soil erosion.

3. Forests are a natural habitat for many species of plants and animals, providing a home for biodiversity and helping to maintain a healthy ecosystem. Forests also provide refuge and food for many endangered species, helping to preserve these species and their habitats.