The nucleus of an atom consists of MCQ with Answer and Explanation

Explanation:
Human hearing range is about 20 Hz to 20 kHz. Sound above 20 kHz is ultrasound. Infrasound is below 20 Hz. Ultrasound used in medical imaging (sonography), cleaning, SONAR.

Explanation:
Beats occur due to interference of two waves with slightly different frequencies (Δf small, typically < 10 Hz for audible beats). The beat frequency is |f₁ - f₂|, causing periodic loudness variation. Same frequency (A, B) produces steady interference (no beats); very different frequencies (D) produce rapid fluctuations not perceived as beats. Memory aid: 'Beats: |f₁ - f₂| small ⇒ audible pulsations; used in tuning'. This wave phenomenon question tests superposition understanding, frequently examined in competitive exams. Always link beat perception to frequency difference magnitude; competitive exams often test qualitative conditions for observable beats.

Explanation:
Higher pressure inside, boiling point >100°C, food cooks faster.