Sunday, December 28, 2014

CBSE X Mathematics Sample Paper -2015

Science Sample Paper -2015
Section A
1. If the equation kx2+ 4x+ k=0 has two equal roots, then

(a) k = ±2 (b) k = 0 (c) k = 2 (d) none of these

2. If the sum of n terms of an A.P., is 2n2 +4n, then its nth term is

(a) 4n + 2 (b) 4n + 5 (c) 10n - 4 (d) none of these

3. If tangents TA and TB from a point T to a circle with center O are inclined to each
other at an angle of 70° then <TOA is equal to

(a)80° (b) 70° (c) 55° (d) 50°

4. To divide a line segment AB in the ratio 5:3, first a ray AX is drawn so that < BAX
is an acute angle and then at equal distances points are marked on the ray AX such that the minimum number of these points is

(a) 12 (b) 11 (c) 10 (d) 8

5. If the circumference and area of a circle are numerically equal, then diameter of the
circle is 

(a)2x (b) 2 (c) 4 (d) 4x

6. The number of solid spheres, each of diameter 2 cm that could be moulded to form a solid metal cylinder of height 45 cm and diameter 4 cm is

(a)14 (b) 15 (c) 135 (d) none of these

7. From the top of a cliff 20 m high the angle of elevation of a tower is found to be equal to the angle of depression of the foot of the tower. The height of the tower is

(a)40 m (b) 60 m (c) 90 m (d) none of these

8. If the distance between the points (5, r) and (1, 0) is 5, then r is

(a)5 (b) -5 (c) 0 (d) + - 3

9. The area of a triangle with vertices A(4, 0), B(7,0) and C(9, 5) is

a)14 sq. units (b) 28 sq. units (c) 17.5 sq. units (d) none

10. If A(5, -1),B(-3, -2) and C(-1,8) are the vertices of triangle ABC, then the length of the median through A is

(a) √50 units (b) √60 units (c) √62 units (d) √65 units

Section B

11. Does there exist a equation whose coefficients are rational but both of its roots are irrational? Justify your answer.

12. The nth term of an A.P., cannot be 2n2 +1. Justify your answer.

13. AB is a chord of the circle and AOC is its diameter such that <ACB = 50°. If AT is the tangent to the circle at the point A, then <BAT is equal to 50°. Justify your answer.

14. Write True or False and give reason for your answer for the following: A pair of tangents can be constructed from a point P to a circle of radius 6 cm situated at a distance of 5 cm from the centre.

15. Is it true that the distance travelled by a circle wheel of diameter x cm in one revolution is 2px cm? Why?

16. A circle is inscribed in a square of side x cm and another circle is circumscribing the square. Is it true to say that area of the outer circle is two times the area of the inner circle? Give reasons for your answer.

17. Write True or False and justify you answer for the following:
A spherical steel ball is melted to make 10 new identical balls. Then, the radius of each new ball is 1/10th radius of the original ball.

18. A hemisphere is cut out from the top of the cylinder with radius equal to the radius of cylinder. Taking radius as r and height of cylinder as h. find total surface area of solid?
Section C

19. 50 circular plates, each of radius 7 cm and thickness 1/2 cm are placed one above another to form a Solid right circular cylinder. Find the total surface area and the volume of the cylinder so formed

20. A bag contains cards which are numbered from 2 to 100. A card is drawn at random from the bag. Find the probability that it bears (i) a two digit number (ii) a number which is a perfect square

21. In an AP, the sum of first ten terms is -150 and the sum of its next ten terms is -550.Find the AP.

22. Construct a triangle ABC in which BC=9 cm, <B=60° and AB=6 cm. then construct another triangle whose sides are 2/3 of the corresponding sides of tri. ABC.

23. If (1,2), (4, y), (x, 6) and (3, 5) are the vertices of a parallelogram taken in order, find the values of x and y.

24. Two tangents PA and PB are drawn to a circle with centre O from an external point P. prove that <APB=2 <OAB.

25. A pole 5 m high is fixed on the top of a tower. The angle of elevation of the top of the pole as observed from a point A on the ground is 60° and angle of depressionof point A from the top of the tower is 45°.Finf the height of the tower. [Take p =1.73].

26. A coin is tossed 3 times. List the possible outcomes. Find the probability of getting at least 2 heads.

27. ABC is a triangle right angled at A. Semicircles are drawn on AB, AC and BC as diameters. Find the area of the shaded region.

28. A canal is 300 cm wide and 120 cm deep. The water in the canal is following with a speed of 20 km/h. How much area will it irrigate in 20 minutes if 8 cm of standing water is desired?

Section D

29. The interior of building is in the form of a cylinder of diameter 4 cm and height
3.5 m, surmounted by a cone of the same base with vertical angle as a right angle. Find the surface area (curved) and volume of the interior of the building.

30. An AP consists of 37 terms. The sum of three middlemost terms is 225 and sum of last three terms is 429. Find AP.

31. Prove that the lengths of the tangents drawn from an external point to a circle are equal.

32. The angles of depression of the top and bottom of a building 60 metres high as observed from the top of a tower are 30° and 60°, respectively. Find the height of the tower and also the horizontal distance between the building and the tower.

33. A train travels at a certain average speed for a distance of 63 km and then travels a distance of 72 km at an average speed of 6 km/h more than its original speed. If it takes 3 hours to complete the total journey, what is its original average speed?

34. The mid-points D, E, F of the sides AB, BC and CA respectively of a triangle ABC are (3, 4), (8, 9), and (6, 7). Find the coordinates of the vertices of the triangle.

By JSUNIL , JSUNIL Tutorial Panjabi colony Gali 01 Email :

Thursday, December 25, 2014

X Revision before exam Chemistry: NCERT Chapter - Periodic Classification of elements

Gist of Lesson for Quick Revision (By JSUNIL)1. Periodic table: The table which classifies all the known elements on the basis of their properties in such a way that elements with similar properties are grouped together.

The first classification of elements was as metals and non-metals. 

In 1789, Lavoisier first attempted to classify the elements into two divisions namely Metals and Non-metals

This served only limited purpose mainly because of two reasons: 

(i). All the elements were grouped in to these two classes only. The group containing metals was very big. 
(ii)  Some elements showed properties of both-metals and non-metals and they could not be placed in any of the two classes.

2. All earlier attempts on the classification of the elements were based on their atomic weights.

3. The first attempt towards the classification of elements was made by Johann Dobereiner, a German chemist in 1829. He made sets of three elements which showed similar chemical properties and he called it triads. as their oxide are alkalies in nature and exist in the Earth

12. No Place were given for forth coming elements by Newland.

13. . Newland placed unlike elements in same slot like Co and Ni placed with F , Cl  and Iodine

14. When Nobel gases were discovered in 1900 law of octave fail and 9th element became similar to 1st. in Newland Octave

4. The Triad was approximately the mean of the atomic weights of the other two members and the properties of the middle element were in between those of the other two members.

5. The average of the atomic masses of Li and K =1/2(7+39 )= 23 (Na)
5. The major drawback of Dobereiner classification was that the concept of triads could be applied to limited number of elements. It was also possible to group quite dissimilar elements into triads.

6.  Lithium, Sodium, Potassium are called Alkalies metal as they react with water and form alkalies (Caustic solution)

7.  Calcium, Strontium, Bromine are called Alkalies Earth metal  as they react with water and form salt and exist in the Earth.

8.  Chlorine, Bromine, Iodine are called Halogen as they are reactive non-metallic elements which form strongly acidic compounds with hydrogen from which simple salts can be made.

9. In 1864 John Alexander Newland, an English chemist noticed that “when elements are arranged in the increasing order of their atomic masses. He found that  "every eighth element had properties similar to the first element.”

10. Newland called this as the Law of Octaves due to its similarity with musical notes .

11. Newland could arrange elements in this manner only up to calcium (atomic mass 40 ) out of a total of over sixty elements known at his time.

15.  Doberenier‘s triads also exist in the column of Newland octaves like Li, Na, K.

16. In1869 Mendeleev a Russian chemist while trying to classify elements discovered that on arranging in the increasing order of atomic mass, elements with similar chemical properties occurred periodically.

17. A periodic function is the one which repeats itself after a certain interval.

18. According to the periodic law : The chemical and physical properties of elements are a periodic function 
of their atomic masses.

19. Mendeleev believed that atomic mass of elements was the most fundamental property. A tabular arrangement of the elements based on the periodic law is called periodic table.

20. The Seven horizontal rows present in the periodic table are called periods.

21. Properties of elements in a particular period increase or decrease  from left to right.

22. The nine vertical columns present in it are called groups  and are numbered from I to VIII and Zero (Roman numerals).

23. Mendeleev’s periodic table had some blank spaces  for undiscovered elements

24. Scandium, gallium and germanium, discovered later, have properties similar to Eka – boron, Eka–aluminium and Eka–silicon, respectively.

25. The Mendellev's periodic table helped in correcting the atomic masses of some elements based on their positions in the table.

26. Atomic mass of beryllium was corrected from 13.5 to 9. With the help of this table, atomic masses of indium, gold, platinum etc., were corrected.]

27. Mendeleev fail to give fixed position to hydrogen in the Periodic Table. It was placed in group IA and group VI B.

28. Hydrogen resembled both the alkali metals and the halogens. So, it was placed above both the groups and could not be given a fixed position in Mendeleev’s Periodic Table.

29. There is no place given for isotopes in Mendeleev’s Periodic Table

30. Different isotopes of same elements have different atomic masses; therefore, each one of them should be given a different position in the periodic table. On the other hand, because they are chemically similar, they had to be given same position.

31. There are anomalous pairs of elements in Mendeleev’s Periodic Table : At certain places, an element of higher atomic mass has been placed before an element of lower atomic mass. For example, Argon (39.91) is placed before potassium (39.1)

32. Disimilar elements placed together: Noble metals like Cu, Ag and Au are placed along with chemically dissimilar alkali metals in Group I . Similarly, Mn possessing very few similarities with halogens have been placed in VII group.

33. Similar elements separated: In Mendeleev's periodic table, certain chemically similar elements such as copper and mercury; gold and platinum have been placed in different groups.

34. Anomalous pairs : In the Mendeleev's Table based on atomic weight, the positions of certain pairs , e.g. Argon( at. wt = 39.94) and potassium ( at. wt = 39.1) : Cobalt( at wt =58.93 ) and nickel ( at wt = 58.71 ) ; Tellurium at wt = 127.60) and iodine (atomic weight = 126.90 ) would be reversed. In other words, certain pairs of elements are misfit in the periodic table, if atomic weight is the basis of classification.

35. The formulae for the oxides of the following elements: K, C, AI, Si, Ba. according to Mendeléev’s Periodic Table are:  K(potassium) belongs to group I. Thus, formula of its oxide is K2O, similarly CO2, Al2O3, SiO2,, BaO.

36. The criteria used by Mendeleev in creating his periodic table are:
 (1) The chemical and physical properties of an element is the periodic function of its atomic mass
.(ii) The elements were arranged in a period such that their properties changed from metallic to non-metallic.(iii) The elements were arranged in groups, such that all the elements have same, but graded physical and chemical properties.

37. The noble gases are placed in a separate group because (a) Noble gases are chemically inactive and hence constitute a separate group.(b)2. Noble gases as a group offer a perfect dividing line for starting a new period in the periodic table.

38. Moseley showed that the atomic number of an element is a more fundamental property. The ModernPeriodic Law can be stated as : ‘Properties of elements are a periodic function of their atomic number.’

39. The Modern Periodic Table has 18 vertical columns known as ‘groups’ and 7 horizontal rows known as ‘periods’.

40. The elements present in any one group have the same number of valence electrons. The number of electrons in the valence shell determines the group of the element. If the element has 1 or 2 electrons, then it belongs to group 1 or 2, respectively. If the element has 3 to 8 electrons, then its group is equal to 10 + number of valence electrons.

41. Elements with the same number of occupied shells are placed in the same period. For example, if an element has 4 electron shells, it belongs to the 4th period.

42. The atomic size depends on the distance between the centre of the nucleus and the outermost shell of an isolated atom.

43. The atomic radius decreases in moving from left to right along a period. This is due to an increase in nuclear charge (increase in no. of proton without increasing shell) which tends to pull the electrons closer to the nucleus and reduces the size of the atom.

44. The atomic size increases down the group. This is because new shells are being added as we go down the group. This increases the distance between the outermost electrons and the nucleus so that the atomic size increases in spite of the increase in nuclear charge.

45. The valencies of all elements of the same group are the same. The valence of an element with respect to oxygen is equal to its group number.

46. The melting points and boiling points decrease while moving down in group of metals.

47. The melting points and boiling points increases while moving down in group of non-metals.

48. Metallic character of the element decreases along a period because the effective nuclear charge acting on the valence shell electrons increases due to decrease in atomic size.

49. Metallic character of the element Increases while moving down in group because the effective nuclear charge experienced by valence electrons is decreasing as the outermost electrons are farther away from the nucleus(due to increase in atomic size).

50. Metals tend to lose electrons while forming bonds.  That is why they are electropositive in nature.

51. Non-metals are electronegative as they tend to form bonds by gaining electrons.

52. The tendency to gain electrons increases in a period due to decrease in atomic size.

53. The tendency to lose electrons increases in a group due to increase in atomic size

54. Non metallic character decreases down in group because of decrease in tendency to gain electron which is due to increase in atomic size.

55. Non metallic character increases left to right in group because of increase in tendency to gain electron which is due to decrease in atomic size.

Periodic properties
Left to right in period
Down a group
Atomic size
Tendency to lose Electron
Tendency to gain Electron
Metallic Character
Non - metallic Character
Distance b/w  Valance Electron and Nucleus
Force of attraction b/w Valance Electron and Nucleus

56. Alkali Metals: Lithium, sodium, potassium, rubidium, caesium and francium have one electron in the valence shell. They are called alkali metals because their hydroxides are strong alkalis.
57. Halogens: The elements placed in group 7 (VIIA) and have seven electrons in their valence shell and so are mononvalent.All these elements form salts called halides, e.g. NaCl, NaI, KCl, KI etc. Halogen is an ancient Greek word meaning 'salt producer.
58. Transition Elements: Elements belonging to 3 to 12 groups are called transition elements. They are called transition elements because they are placed between the most reactive metals on the left and non-metals on the right.
59. Inner-transition Elements: 
The 6th period consists of elements that have atomic numbers 58 to 71. They are called Lanthanides. 

The 7th period consists of elements that have atomic numbers 90 to  105. They are called Actinides. Both of them are called inner transition elements.

60. The group VIA elements are called chalcogens because most ores of copper (Greek chalkos) are oxides or sulfides, and such ores contain traces of selenium and tellurium.

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Sunday, December 7, 2014

Ch-Our Universe - Solved Question Basic science class 8 Bharati Bhawan Publication

Trend Setter Basic Science Publication - Bharati Bhawan Solutions

Very Short Answer type Questions

A1.Is light year a unit of time or distance? Define `1 light year?

Ans: Light year is a unit of distance .one light year is a distance covered by light in 1 year.

A2.What is the source of stars energy?

Ans: The source of stars energy is nuclear fusion in which hydrogen atoms split up into helium atoms and large amount of energy is librated.

A3.What gives galaxies different shapes? Name a few common shapes of galaxies.

Ans: The arrangement of stars gives galaxies different shapes of galaxies. About 100 billians galaxies in the universe some of them are in shape of spiral, ring like or elliptical.

A4.What is the big Dipper?

Ans: The seven brightest stars in between the month of February and may form a shape of dipper in northern sky. This constellation  is called Big deeper or Saptarshi.

A5. Why are Mercury venues, and Mars called terrestrial planets?

Ans: This is because they are closest to sun and rocky like earth.

A 6. Name the planet which have ring around them?

Ans: Saturn, Jupiter , Uranus and Neptune 

A7. What is the huge spot on Jupiter?

Ans: This spots are actually  a huge storm, which has been ranging on Jupiter for more than 300 years

A8. Name two dwarf planets?Ans: Ceres and Eris

A9. How do dwarf planets different from other planets?

Ans: dwarf planets are not able to pull in the object (gravitational force) near its orbit at the time of its formation

A10.Why do scientists think that Mars had liquid water in the past?

Ans: Scientists think that Mars had liquid water in the past as the channels visible on its surfaces.

Short Answer type Questions

B1. What re the difference between stars and planets?

Stars are:          a. luminous                   b. Stationary

Planets are :      a. Non luminous            b. Movable

B2. What re the difference between galaxy and constellation?

Ans: (i) The first difference is that a galaxy is a collection of billions of stars whereas a constellation is a collection of only a very few stars.

 (ii) The second difference is that a galaxy does not form a definite pattern which resembles the shape of an animal or a human being but a constellation appears to resemble an animal or human being  in its shape

B3. What are the asteroids?      

Answer: There is a large gap in between the orbits of the Mars and Jupiter. This gap is occupied by a large number of small bodies that revolve around the sun. These are called asteroids

B.4.What is meteorites? In which bodies are meteorites craters more commonly found and why?

Ans: meteorites are rocky bodies revolving around the sun. Large meteors when hit the surface of planet create craters. Meteorites craters more commonly found on those planets and moon which have no or little atmosphere to burn off the falling rocks. E.g. Moon and mercury.

B5. What is comet? How is its tail formed?

Ans:  Comet is small body of ice and dust revolving around the sun in its elongated orbit. When comet approaches the sun, it heats up and leaves behind a stream of hot glowing gases and dust particles. We see it as a tail. 

B6. Why does geostationary satellite seem fixed above a point on the earth?

Ans: A satellite placed at about 3600 km above the equator completes one revolution around the sun in 24 hrs . This makes its position fixed above a point on the earth               

More solved question Trend Setter

VIII Stars and The Solar System (Physics) Formative and Summative Assessments