UPSC 2021: With reference to street-lighting, how do sodium lamps differ from LED lamps? 1. Sodium lamps produce light in 360 degrees but it is not so in the case of LED lamps. 2. As street-lights, sodium lamps have longer life span than LED lamps. 3. The spectrum of visible light from sodium lamps is almost monochromatic while LED lamps offer significant colour advantages in street-lighting. Select the correct answer using the code given below.

Low/High-pressure sodium lamps emit light in all directions (360°), whereas LEDs are inherently directional (~180°); hence Statement 1 is true ([stouchlighting.com](https://www.stouchlighting.com/blog/top-15-advantages-of-led-lighting?utm_source=openai)). LEDs typically last 5–6 times longer (≈50,000 h or more) than sodium lamps (≈15–24 000 h), so Statement 2 is false ([stouchlighting.com](https://www.stouchlighting.com/blog/led-vs-hps-lps-high-and-low-pressure-sodium?utm_source=openai)). Sodium lamps, especially low-pressure types, emit almost monochromatic yellow light (~589 nm), giving very poor colour rendering, while LEDs can be designed for broad spectra, so Statement 3 is true ([en.wikipedia.org](https://en.wikipedia.org/wiki/Sodium-vapor_lamp?utm_source=openai)).