Article Detail Which is the longest day in the year ? Answer: June 21 Similar Questions : 1. Which is the lightest metal ? Answer: Lithium 2. Which is the highest waterfall in the world ? Answer: Angel, Venezuela 3. Which Indian state is having longest coastline ? Answer: Gujrat 4. Which is Longest road tunnel in the World ? Answer: Lærdal Tunnel (Norway - 24.51 kilometre) 5. Which is Longest national highway of India ? Answer: NH-7 ( Varanasi to Kanyakumari - 2,369 km) 6. Which is the largest gulf ? Answer: Gulf of Mexico 7. Which is the Densest populated State of India ? Answer: West Bengal Read more from - Longest and Largest