# Important Questions for Class 8 Chapter 12-Exponents and Powers

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**Important questions based on NCERT syllabus for Chapter 12-Exponents and Powers:**

*Question 1*: Simplify :(−2/3)^8 × (−2/3)^5 × 72^9

*Solution*:

(−2/3)^8 × (−2/3)^5 × 72^9

= (−2/3)^{(8+5)} × 3^6

= (−2/3)^{(13)} × 3^6

= −(2^13/3^7)

*Question 2*: Simplify : [{(−5)^5 × (−5)^{−10}} ÷ 25] × 10^5

*Solution*:

[{(−5)^5 × (−5)^{−10}} ÷ 25] × 10^5

[{(−5)^{(5−10)}} ÷ 25] × 10^5

[(−5)^{−5} × 2^{−5}] × 10^5

[(−1)^{−5} (5)^{−5} × 2^{−5}] × 10^5

[−(10)^{−5}] × 10^5

= −1

*Question 3*: Mass of A is 9.97×10^{24}kg and mass of B is 6.35×10^{22}kg. What is the total mass?

*Solution*:

Total mass = 9.97 × 10^{24}kg + 6.35 × 10^{22} kg

= 997 × 10^{22} + 6.35 × 10^{22}

= (997 + 6.35) × 10^{22}

= 1003.35 × 10^{22} kg

= 1.00335 × 1025 kg

*Question 4*: If 15625 = (x)^2 = 5^(y) . Find the value of x and y.

*Solution*:

15625 = (x)^2 = 5^(y)

Prime factorisation of

15625 = 5 × 5 × 5 × 5 × 5 × 5 = 5^6 = 125^2

x = 125

y = 6