A man walking at 5 km/h reaches his office 10 minutes late. If he walks at 6 km/h, he is 5 minutes early. Distance to office is MCQ with Answer and Explanation

Explanation:
Standard atmospheric pressure at sea level is 101,325 Pa, approximately 10⁵ Pa (or 1 bar, 760 mm Hg). This value is crucial for pressure calculations in fluids, thermodynamics, and meteorology. Option B (1000 Pa) is too low (about 1% of atmospheric), C and D are orders of magnitude off. Memory tip: 'Atmospheric pressure ≈ 10⁵ Pa = 100 kPa = 1 bar'. This factual knowledge is frequently tested in competitive exams as a baseline for pressure-related problems. Always use SI units (Pascal) unless specified otherwise.

Explanation:
Covering part of a lens reduces the amount of light reaching the image, making it fainter, but the entire image is still formed because light from each object point can pass through the uncovered portion and converge to the corresponding image point. Image position, size, and nature remain unchanged. Memory aid: 'Partial lens coverage ⇒ reduced intensity, not partial image'. This conceptual question tests understanding of image formation principles, commonly featured in competitive exams to identify misconceptions about ray optics. Always recall that every point on lens contributes to entire image.

Explanation:
T = 2π√(m/k): depends on mass and spring constant only, not gravity. Weightlessness doesn't affect spring force. Memory aid: 'Spring period: independent of g; pendulum period: depends on g'. Oscillations concept frequently tested in competitive exams.