A sound wave has wavelength 1.7 m and speed 340 m/s. Its frequency is MCQ with Answer and Explanation

Explanation:
Leading zeros not significant. '2040' – trailing zero after decimal is significant. So digits 2,0,4,0 are significant = 4. Rule: zeros between non-zero and trailing zeros after decimal count.

Explanation:
ΔL = L₀αΔT = 1×2×10⁻⁵×50 = 100×10⁻⁵ = 10⁻³ m = 1 mm. Direct expansion formula application. Memory tip: 'ΔL = LαΔT; convert result to required units'. Tests thermal expansion calculation with unit conversion, frequently appearing in competitive exams.

Explanation:
Ice displaces water equal to its weight. When melted, it occupies exactly that volume. So level unchanged. Classic question.