Power Play — Quiz

Q1. Priya checks the fold-thickness table. After 17 folds, the thickness of the paper is approximately

• A. about 17 cm
• B. about 65 cm
• C. about 131 cm
• D. about 1024 cm

Q2. Ravi reads. After 30 folds, the thickness of the paper is about 10.7 km — the typical height at which

• A. tall buildings stand
• B. clouds form
• C. satellites orbit
• D. planes fly

Q3. In the Magical Pond the number of lotuses doubles every day and the pond is fully covered on day 30. On which day was the pond half covered?

• A. Day 15
• B. Day 28
• C. Day 30
• D. Day 29

Q4. Writes the thickness after 7 folds as 0.001 cm × 2^7. The value of 2^7 used here is

• A. 128
• B. 64
• C. 256
• D. 49

Q5. Figure it Out Q1(ii) asks to express y × y in exponential form. The correct answer is

• A. y^2
• B. 2y
• C. y + y
• D. 2^y

Q6. Is (−2)^4 = 16? Verify. Which working is correct?

• A. (−2)^4 = −2 × 4 = −8
• B. (−2)^4 = −(2^4) = −16
• C. (−2)^4 = (−2)(−2)(−2)(−2) = 16
• D. (−2)^4 = 2 × 4 = 8

Q7. Generalises the product law for exponents. If a and b are counting numbers, then n^a × n^b equals

• A. n^(a × b)
• B. n^(a − b)
• C. (2n)^(a + b)
• D. n^(a + b)

Q8. 4^6 can be written as a power of a power. Which of these is one such correct form?

• A. (4^3)^2
• B. (4^2) + (4^4)
• C. 4 × 6
• D. (4 + 4)^3

Q9. Using the quotient law the value of 2^4 ÷ 2^3 in simplest exponential form is

• A. 2^7
• B. 1
• C. 2^12
• D. 2^1

Q10. Using the rule m^a × n^a = (mn)^a to rewrite 3^4 × 2^4, the single-base form is

• A. 5^4
• B. 5^8
• C. 6^4
• D. 6^8

Q11. Halving a line of 2^4 units ten times gives 2^(−6) units. The value of 2^(−6) is

• A. −64
• B. 1/12
• C. 64
• D. 1/64

Q12. The quotient law n^a ÷ n^b = n^(a − b). The rule for n in this law is that n must

• A. not be zero
• B. be a prime number
• C. be greater than 10
• D. be a positive integer only

Q13. Scientific notation is defined as x × 10^y. For the form to be a valid standard form, the coefficient x must satisfy

• A. 1 ≤ x < 10
• B. x is any whole number
• C. x is between 0 and 1
• D. x equals 10

Q14. Writes the 2 crore population of Mumbai in scientific (standard) form. The correct form is

• A. 2 × 10^5
• B. 2 × 10^6
• C. 2 × 10^7
• D. 2 × 10^8

Q15. The global ant population as 2 × 10^16 and the human population as 8 × 10^9. Roughly how many ants are there for every human?

• A. 2.5 hundred
• B. 2.5 thousand
• C. 2.5 lakh
• D. 2.5 million