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Which One  is more reactive between K and Na? Why?

Both K and Na lie first group of modern periodic table both have same number of valence electron. But for K there is more number of shell than Na so less force of attraction between nucleus and valence electron set on the K than Na. Therefore, K can easily  loss their outermost electron because of these reason K is more reactive than Na.

 If you can give any other reason you can comets me please.


Why F is more reactive than Cl?


Both F and Cl are non-metal and lies in VIIA group of modern periodic table. Both have 7 electron in outermost orbit they are non-metal and they needs 1e- to become stable. The number of orbit in F is less than Cl so force of attraction between nucleus and valence electron of F is more than that of Cl. Therefore F can attracts electron easily than Cl so, F is more reactive than Cl.

Question Set Of Science


PHYSICS

1. A. Define free-fall. Write down the conclusion drawn from the coin and feather experiment. Calculate the mass of the earth if the radius of the earth is 6.4 × 106 m and g = 9.8 m/s2 .                           (1+1+2.5)                                                                                   

B. In the context of Nepal " bio-mass energy is the best source of alternative energy". Justify the statement. The hydroelectricity is an an indirect source of solar energy. Clarify the statement.             (1+2)

2. A. What is the relation between density and up-thrust of a liquid?  Lower portion of dam is made stronger than upper portion, why? Write one advantage and one disadvantage of anamolous expansion of water.                   (0.5+2+2)

B. State Pascal's law. What amount of water is displaced when a piece of ice of volume 30,000 cm3 is placed in water. Density of ice is 0.92 g/cm3.        (1+2)

3. A. If three liquids A, B and C having equal masses are taken in three same size beakers and exposed in the sunlight. After one hour the increased temperature in each is shown in the table below.
Liquid
Increased temperature
Mass
A
800C
1 kg
B
600C
1 kg
C
330C
1 kg

i)                    Which liquid has the lowest the specific heat capacity and why?
ii)                  If all the three liquids are heated to the same temperature and put in the same beakers separately, which one cools down at last and why?  (1.5+1.5)
B. What is magnification of lens? What is long sightedness? State the two causes of the defect and draw the diagram to show how this defect can be corrected. (1+0.5+2)
4. A. Write any two differences between a filament lamp and a fluorescent lamp. In a house, 10 bulbs of 60 watt, 4 bulbs of 100 watt and a 750 watt refrigerator are connected in 220 volt and used for 5 hours daily. Calculate the total electricity consumption in a month.      (2+2)
B. What is motor effect? What type of transformer is used in the radio, TV, etc.? Find out the voltage in the secondary coil having 400 turns provided with 220 V primary voltage in the primary coil of 2000 turns.                  (1+0.5+2)
                                      CHEMISTRY
5. A. Write any two characteristics of modern periodic table. Study the given table and answer the following questions.
Elements
Electronic configuration
A
1S2,2S2,2P6,3S1
B
1S2,2S2,2P6,3S2,3P6,4S1
C
1S2,2S2,2P6
i)                    What is the valency of C?
ii)                  Which is more active between the element A and B, why?  (2+0.5+1.5)
B. Draw a neat and well labeled diagram for the preparation of carbon dioxide gas in the laboratory. Write the structural formula of ethyl alcohol. Name the compound below:              H – C = C – H.  Is it saturated or unsaturated hydrocarbon, why?                                                                (2+0.5+1)
6. A. Which metal is obtained from haematite?  Write the chemical equation for the reaction between this metal and dilute sulphuric acid. What is the pH value of the neutral substance? Write with an example. (0.5+2+0.5+0.5)
B. What are the substances used to make lead crystal glass? Environmentalists request to avoid the use of plastic, why? (2+2)              
                                    BIOLOGY
7. A. Draw the diagram of a virus and label any two parts. What is reflex action? Write the name of hormone that controls sugar in the blood. Give one example of positive photo taxis.                                           (2+1+0.5+1)
B. Define heart beat? Write any two differences between auricle and ventricle.                 (1+2)
8. A. Define meiosis cell division. It is called reductional cell division, why? Write the two significance of this cell division. (1+1.5+2)
B. Write any one difference between primary mycelium and secondary mycelium. Write any two advantages that can be obtained from the vegetative propagation by farmers. (1+2)
9. A. What is hybrid? Draw a chart to show the result obtained in the first and second filial generation by crossing a black rat and white rat according to Mendelism. (1+2.5)
B. What is nitrogen fixation? Write one phylum or division of the following living beings with one major character.
I) bat   ii) sea horse    iii) cycas    (1+3)
                        ASTRONOMY AND GEOLOGY
10. A.  Scientists have said that human beings and the earth did not come into existence at the same time, why?  How is fossil formed? What is the importance of ozone layer? (1+1.5+1)   
B. Write any two differences between meteor and comet. Name one spiral galaxy. How is red giant star formed?  (2+0.5+1.5)    
                                         THE END  

Question Set Of Science--2


Group A                                                                15 × 1 = 15



1.       Define weightlessness?

2.       Define G in terms of gravitational force between two masses.

3.       Define 1pascal Pressure.

4.       What do you mean by Hydrometer?

5.       Define Alternative sources of energy.
6.       Define Specific heat capacity.
7.       Define eddy current in transformer.  
8.       What do you mean d-Block element?
9.       Define Double displacement reaction with example.
10.    Define Weak acid with example.
11.    Write down the scientific name of SERI silkmoth.
12.    What do you mean by Royal Jelly?
13.    Define Central Nervous system.
14.    Which Era is known as time of Reptiles?
15.    Define Ionosphere.

                                                Group B                                                                13 ×2 = 26
1.       Why value of ‘g’ is not same for pole and Equator reason of Earth? What is the value of g at the centre of earth?
2.      What do you mean my Energy Crisis? How to control in future.
3.      An Egg is sink in water but same egg is float on salt water why?
4.       Water is used to cool hot engines of vehicles why?
5.       Write down Faraday's laws of electromagnetic induction.(any two laws)
6.       Which one is less reactive F and Cl, why give suitable reason.
8.       How to prepare base write any one chemical reaction.
9.       Classify Silkworm and write its scientific name of SERI.
10.    Which glands secrete insulin and write their function.
11.    How to control air pollution. Write any three measures
12.    What do you mean by Fossil Fuel? Write any two important of Mineral Oil.
13.    The earth is a Natural Green House describe it.


                                Group C                                                               6 × 3 = 18
1.       Tides occur in oceans but not in lakes. A person can lift a mass of 100kg on the surface of the earth. What amount of mass can he/she lift on the surface of the moon?
2.       An ice cube of volume 0.03 m3 floats on water. The density of ice and water are 900kg/m3 and 1000 kg/m3 respectively. What fraction of the volume of the ice would be in air? What would be the height of the ice cube in air if its total height is 0.2m?
3.       If 20ml of tea at 90oC is mixed with 10ml of milk at 15oC, what will be the final temperature of the mixture? Assume that the specific heat capacity of milk equal to that of the tea.
4.       State Henery moseley Law. Write down the orbital configuration of Potassium and Sulphur.
5.       Pickle cannot be stored in a metal vessel for a long time, why? Define exothermic reaction with one example.
6.       What is a cocoon? What is metamorphosis? Define Hormones.
7.        
Group D                                                              4× 4 = 16
1.      Established the relation of g at the height of the Earth 'h' if the radius of the Earth is 'R'.  Define nuclear fission reaction.
2.       A thick glass tumbler cracks when hot water is poured into it. Define Anomalous expansion of water.
3.       In a house, an electric bulb of 60W is used for 15 hours and an electric heater of 750W is used for 10 hours every day. Calculate the cost of using the bulb and the heater for 30 days if the cost of one unit of electrical energy is Rs 7.
4.       Why are fossils preserved is sedimentary rocks only? Define Ozone layer and how to protect from Depletion.







Important Question of 10 Class Science and Numericals;