Science gk

 1.Which gas is present under pressure in soft drinks? 

Carbon monoxide

2. Equal volumes of all gases at the same temperature and pressure contain equal number of molecules this law is called as... 

gay lussac's law

3.KMnO4 can be used as..

 disinfectant

4.Which of the following disease is this spread through here..

 tuberculosis

5.Angora wool is obtained from a breed of.. rabbit

6. Sake is a favourite wine of Japanese it is made from.. rice grains

8.Cover of capsule is made of.. starch

9.Turpentine oil is obtained from.. pine tree

10.The bill for electricity consumption is based on the measurement of.. wattage

11.Alcoholic beverages contain ethyl alcohol

12.Biological pest control is carried out by Scorpion and spiders

13.Number of naturally occurring amino acid found in proteins is 20

14.In the visible spectrum the colour having the shortest wavelength is red

15.Ragini snake belongs to the category of cold blooded animals

16.If one wants to throw a cricket ball to the maximum distance then he should show it at the angle of 45 degree

17.Water has maximum density at 4 degree centigrade

18.In -40° centigrade and fahrenheit temperature are same

19.Open Akash first established the first that the Earth revolves round  the sun

20.Ajolla gives in good bio fertilizer when mixed with blue green algae

21.Ammonia gases used for refrigerator

22.Aspirin is the common name of acetylsalicylic acid

23.Mercury vapour lamp is the most intense man-made light source

24.Resinous Shellac is obtained from bark of a tree

25.Methanol  is added to industrial ethanol to make it suitable for human consumption

26.Urea was the first organic compound to be synthesised in the laboratory 

27.Domestic Inspector control by an ultrasonic sound

28.Azolla is used as good bio Fertilizer in rice field

Algebraic Expressions and Identities

Algebraic expressions are expressions formed from the variables and the constants. A variable can take any value. The value of an expression changes with the value chosen for variables it contains.

  A number line has infinite number of points. A variable can take position on number line.

  Expressions containing one, two or three terms are called monomial, binomial and trinomial respectively.

  Any expression having one or more terms is called polynomial.

  A monomial is obtained on multiplying any monomial with another monomial.

  The numerical factor of a term is called its coefficient.

  An identity is a standard equality which is true for all the values of the variables in the equality.

  Few commonly used identities are

        I.   (a + b)² = a² + b² + 2ab

       II.   (a – b)² = a² + b² – 2ab

      III.   (a + b)(a – b) =a² – b²

      IV.   (x + a)(x + b) = x² + (a+b)x + ab

Note – Mainly the above formulas are used to solve all the problems of this chapter.

1.  Find the value of: x² – 1/5 at x= -1.

2.  What is the value of x² + y² – 10 at x = 0 and y = 0?

3.  Find the product of 9a, 4ab and -2a.

4.  Simplify (a + b + c)(a + b - c).

5.  Using identities evaluate: 8.56 * 11.60.

6.  Using identities evaluate: (99)².

7.  Simplify x(2x – 1) + 5 and find its value at x = -2.

8.  Evaluate the value of (95)² using identities.

1.  Which of the following is the numerical coefficient of x²y²?

        I.   0

       II.   1

      III.   x²

      IV.   y²

2.  Which of the following is the numerical coefficient of -5xy?

        I.   5

       II.   -x

      III.   -5

      IV.   -y

3.  pqr is what type of polynomial?

        I.   Monomial

       II.   Binomial

      III.   Trimonial

      IV.   None of these

4.  The value of x² - 5 at x= -1 is-

        I.   -2

       II.   -1

      III.   -4

      IV.   -5

5.  a²-b² is a product of

        I.   (a+b)(a-b)

       II.   (a+b)(a+b)

      III.   (a-b)(a-b)

      IV.   None of these

6.  Which of the following is the value of (x+ 1/x)²?

        I.   x² + 1/x²

       II.   x² - 1/x²

      III.   x² + 1/x² + 2

      IV.   x²+ 1/x² + 2x

7.  Which of the following is obtained by subtracting x²-y² from y² - x²?

        I.   -2(x²-y²)

       II.   -2(x² + y²)

      III.   2(x²+ y²)

      IV.   2(x²- y²)

8.  What degree does x³ - x²y² - 8y²+ 2 have?

        I.   2

       II.   3

      III.   4

      IV.   7

9.  What is the value of 5x²⁵ - 3x³² + 2x^-12 at x=1?

        I.   0

       II.   2

      III.   4

      IV.   None of these

10.  What is the product of (x+a) and (x+b)?

        I.   x²+ (a-b)x + ab

       II.   x² + (a+b)x - ab

      III.   x² + (a+b)x - ab

      IV.   x² + (a+b)x + ab

ANSWERS

        1.    II

        2.    III

        3.    I

        4.    III

        5.    I

        6.    III

        7.    I

        8.    III

        9.     III

        10.  I

Maximum time- 30 minutes

Maximum marks- 20

1.  Add: a + b + ab; b – c + bc and c + a + ac.      (2)

2.  Verify the identity (x + a)(x + b) = x² + (a + b)x + ab for a = 2, b = 3 and x = 4.      (3)

3.  Find the volume of cuboid whose dimensions are (x² – 2); (2x + 4) and (x - 3).      (4)

4.  Write the terms and coefficients of 3 – xy + yz – xz.      (2)

5.  Simplify: (a + b +c)(a + b – c).      (2)

6.  Simplify the expression x(2x-1) + 5 and its value at x = -2.      (3)

7.  Using suitable identities find (xy + 3p)².      (2)

8.  Subtract 5x² – 6y² + 8y – 5 from 7x² – 5xy + 10y² + 5x – 4y.      (2)