Science & Technology Part I Important Questions for Board Exam 2020. 99.99% Sure Questions.

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Science & Technology Part I
Important Questions for Board Exam 2020. 
99.99% Sure Questions. 

Explain what happens when following reaction takes place and give the balanced chemical equation:
[This section contains 5 Important Questions]
Silver nitrate solution is added to a solution of sodium chloride. 
Sodium carbonate solution is added to calcium chloride solution. 
Sulphur dioxide and hydrogen sulphide reacts. 
Potassium chromate solution is added to solution of Barium sulphate.

[This section contains 4 Important Questions]

Redraw and complete the following diagram of a simple microscope. State the Nature of the image. 

Distinguish between :
[8 Important Questions]
Far-sightedness and Near-sightedness. 
s-block elements and p-block elements 
Groups and Periods of Modern Periodic Table 
Alkali metals and Alkaline earth metals 
Inert gases and Normal elements 
Mendeleev’s periodic table and Modern Periodic table.

Give scientific reasons :
[10 Important Question]
Grills of doors and windows are always painted before they are used. 
We cannot clearly see an object kept at a distance less than 25 cm from eye. 
Simple microscope is used by watch repairers. 
It takes time for pieces of Shahabad tiles to disappear in HCl, but its powder disappears rapidly. 
When the gas formed on heating limestone is passed through freshly prepared lime water, the lime water turns milky. 
Stars twinkle at night. 
Respiration is considered to be an exothermic reaction. 

Write down the electronic configuration of the following elements from the given atomic numbers. Answer the following question with explanation :
[6 Important Questions]
19K, 11Na, 4Be
Which of these atoms has the smallest atomic radius? 
13Al, 14Si, 11Na,12Mg, 16
Which of the above elements has the highest metallic character? 
6C, 3Li, 9F,7N, 8O
Which of the above elements has the highest non-metallic character? 
11Na, 15P, 14Cl,14Si, 12Mg 
Which of these has the largest atom? 
3Li, 14Si, 2He,11Na, 15
Which of these elements belong to period 3?

Answer the following: 
[19 Important Questions]
How could the Modern Periodic Table remove various anomalies of Mendeleev’s table? 
What is corrosion? Do gold ornaments corrode? Justify. 
Merits of Modern Periodic table over Mendeleev’s periodic table. 
What is the function of iris in the human eye
Pritesh has spectacles. The power of the spectacles is –2.5D. 
(i) Name the eye defect.
(ii) What is wrong with his eyeball?
(iii) Which spectacles will he use? 
Give four uses of decomposition reaction. 
What is rancidity? Mention only two ways by which rancidity can be prevented. 
State the merits of Mendeleev’s Periodic Table. 
What are the demerits of Mendeleev’s periodic table? 
Explain the types of reaction with reference to oxygen and hydrogen. Illustrate with examples 
The value of ‘g’ at the centre of the Earth is zero. Explain? 
What is the reaction called when oxidation and reduction take place simultaneously? Explain with one example. 
What are the factors which affect the rate of a chemical reaction. 
Answer the following questions based on the concept of total internal reflection : 
(a)  What is the angle of incidence called as when the angle of refraction is 90o
(b)  State any one phenomena in nature which is based on total internal reflection.
(c)  State any one condition required for total internal reflection. 
What is the periodic trend in the variation of valency while going down a group? Explain the answer with reference to group 1, group 2 and group 18. 
Write three laws of Kepler. State Newton’s universal law of gravitation

Write a note 
[7 Important Questions]
Oxidation Reaction. 
Neutralisation Reaction. 
Endothermic Reaction.
Dispersion of light with a neat labelled diagram. 
Redox Reaction.
Reduction Reaction.

Numerical Problems: 
[9 Important Questions]
A tennis ball is thrown up and reaches a height of 4.05 m before coming down. What was its initial velocity? How much total time will it take to come down? Assume g = 10 m/s2. [Hint the ball is thrown against gravity.] 
An iron ball of mass of 3 kg is released from a height of 125 m and falls freely to the ground. Assuming that the value of g is 10 m/s2, calculate (i) time taken by the ball to reach the ground
(ii) velocity of the ball on reaching the ground 
(iii) the height of the ball at half the time it takes to reach the ground 
Draw a ray diagram for object position between 2F1and F1for a convex lens. 
Doctor has prescribed a lens having power +1.5D. What will be the focal length of the lens? What is the type of the lens and what must be the defect of vision? 
An object kept 60 cm from a lens gives a virtual image 20 cm in front of the lens. What is the focal length of lens? Is it a converging lens or a diverging lens? 
The absolute refractive index of water is 1.36. What is the velocity of light in water? (velocity of light in vacuum is 3 × 108m/s) 
Mahendra and Virat are sitting at a distance of 1 metre from each other. Their mass are 75 kg and 80 kg respectively. What is the gravitational force between them? (G = 6.67 × 10–11Nm2/kg2
Let the period of revolution of a planet at a distance R from a star be T. Prove that if it was at a distance of 2R from the star, its period of revolution will be √8 T.

Observe the figure and answer the following question:
[5 Important Questions]
Given below is a diagram showing a defect of human eye : 
Study it and answer the following questions : 
(i)  Name the defect shown in figure. 
(ii)  Give two possible reasons for this defect of eye in human being. 
(iii) Name the type of lens used to correct the eye defect. 

How many times does the light undergo refraction? 
Which two angles are equal? 

Which phenomena does the diagram show? 
Which law obeyed by light makes this phenomena occur? 
Name one more phenomena in nature where the above law is observed. 

Define dispersion of light. 
State the phenomena that occur at point A, B and C. 

[7 Important Questions]
Centre of curvature of a lens 
Principal axis of a lens
Persistence of vision
Distance of distinct vision 
Optical centre of a lens 
Escape velocity and Prove
Balance the following equation stepwise: 
[5 Important Questions]
H2S2O7(l)+ H2O(l) → H2SO4(l)
SO2(g) + H2S(aq) → S(s)+ H2O(l)
Ag(s)+ HCl(aq)→ AgCl ↓+ H2
N2(g) + H2(g) → NH3(g)

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