10 questions · Form 3 Mathematics Bab 2: Standard Form
10 questions · plays in fullscreen
Prefer reading to quizzing? All 10 questions are listed below with the answer and explanation under each one.
1. Calculate (2 × 10⁴) × (3 × 10⁻⁶).
Answer: A
(2 × 3) × 10⁴⁺⁽⁻⁶⁾ = 6 × 10⁻².
2. Evaluate (1.2 × 10³) × (5 × 10⁴) and state the answer in standard form.
Answer: B
(1.2 × 5) × 10³⁺⁴ = 6.0 × 10⁷.
3. The mass of a water molecule is 3 × 10⁻²³ g. Calculate the mass of 4 × 10²¹ water molecules.
Answer: B
Total mass = (3 × 10⁻²³) × (4 × 10²¹) = 12 × 10⁻² = 1.2 × 10⁻¹ g.
4. Which of the following numbers is written in Standard Form?
Answer: C
Standard Form is written as A × 10ⁿ where 1 ≤ A < 10 and n is an integer. 4.5 satisfies 1 ≤ 4.5 < 10.
5. How many significant figures does the number 300.00 have?
Answer: C
Trailing zeros after a decimal point are significant. All 5 digits (3, 0, 0, ., 0, 0) are significant.
6. How many significant figures are there in 0.005040?
Answer: B
Leading zeros (0.00) are not significant. The digits 5, 0, 4, and the trailing zero 0 are significant, giving 4 s.f.
7. Calculate (3.6 × 10⁻⁴) ÷ (9 × 10⁻²).
Answer: A
(3.6 ÷ 9) × 10⁻⁴⁻⁽⁻²⁾ = 0.4 × 10⁻² = 4.0 × 10⁻³.
8. Round 49,960 to 3 significant figures.
Answer: A
Target position is the second 9. Next digit is 6 (≥ 5), rounding up gives 50,000 (which represents 3 s.f. in this context).
9. A rectangular land has length 4 × 10³ m and width 2.5 × 10² m. Find the area of the land in m² in standard form.
Answer: A
Area = length × width = (4 × 10³) × (2.5 × 10²) = (4 × 2.5) × 10³⁺² = 10 × 10⁵ = 1.0 × 10⁶ m².
10. Calculate 3.4 × 10⁴ + 2.5 × 10⁴.
Answer: B
(3.4 + 2.5) × 10⁴ = 5.9 × 10⁴.