An element X has atomic number 17 and mass number 35. Number of neutrons is MCQ with Answer and Explanation

Explanation:
g = GM/R² = G (ρ 4/3 π R³)/R² ∝ ρ R. If radius half, density same, g becomes half. Weight half = 50 N.

Explanation:
Rainbow: sunlight enters raindrop (refraction + dispersion), reflects internally (TIR), exits with further refraction. Primary rainbow: one TIR; secondary: two TIRs. Memory tip: 'Rainbow = refraction + dispersion + TIR in water droplets'. Application question testing atmospheric optics, frequently appearing in competitive exams.

Explanation:
A Wheatstone bridge circuit consists of four arms with resistances P, Q, R, S and a galvanometer in the middle. It is balanced when no current flows through the galvanometer arm. This happens exclusively when the potentials at the two ends of the galvanometer are equal, meaning the potential difference across it is exactly zero (P/Q = R/S).