Page 114 - Maths Skills - 7

112 Maths

B. Fill in the Blanks 3. If the age of our universe is 9000000000000
years nearly then convert the age of universe
1. (2 ) = ________________ into standard form.
3 5
2. 2 + 3 = ________________ 4. If the value of x is 98200000000000 them convert
2
2
the value of x into the standard form.
 −  1
3. Cube of   7  is ________________ E. Assertion-Reason Based Questions

Directions for Questions 1 to 3: In each of the
 7  5  7  3  7  questions given below. There are two statements
4.   ÷   =   marked as Assertion (A) and Reason (R). Mark your
 11   11   11 
answer as per the codes provided below:
5. 7 megabyte = _____________ × 10 bytes. (a) Both A and R are true and R is the correct
[Hint: 1 megabyte = 1000000 bytes] explanation of A.

C. Write ‘T’ for true and ‘F’ for false statements (b) Both A and R are true but R is not the correct
explanation of A.
1. The value of a is 1. (c) A is true but R is false.
1
32  2  5 (d) A is false but R is true.
2. The exponential form of 243 is   · Q. 1. Assertion (A): 4 × 4 = 4 7
3 

5
2
3. (x ) = x m×n Reason (R): a × a = a (m + n)
m n
m
n
97
4. The reciprocal of 6 is 6 . Q. 2. Assertion (A): (–3) = –3 97
–1
Reason (R): (–1) odd number = –1
3
−   5
− 
− 
5.  5 is equal to .  5 × −   5
×
        Q. 3. Assertion (A): 420000000 = 4.2 × 10 8
 3   3   3   3 
Reason (R): A number in standard form is a × 10
n
D. Case Study Based Questions where 1< a < 10 and n is a non zero integer.
Exponents are very useful to express immense number
such as 6,000,000,000 which is 6 × 1000,000,000 as SUBJECTIVE TYPE QUESTIONS
6 × 10 and small number such as 0.000,000,006 as F. Solve the following word problems
9
6 –9 1. What power of 6 is 1296?
1000000000 = 6 × 10 . When a number is expressed
with one whole number and the remaining part as 2. What power of – 3 is –2187?
exponents of 10, then the number is in standards form. 3. Manu is enlarging a photo on her computer
screen. The photo is 3 cm wide. Each time she
Answer the following questions on the basis of the enlarges the photo, its width is doubled. If she
above data. enlarges the photo five times, what is the final
1. The milky way is 10000000 light year away width of the photo?
convert the number into standard form. 4. The dimensions of a water tank is a mm by a 5
2
2. Convert the number into standard form. The mm by 3b mm. If 1 mL of water contains 3c
21
2
coefficient of linear expansion of copper is water molecules, how many molecules are there
0.0000187. in water tank?