Questions

Buying and selling goods over the internet is called E - Commerce.

The boring of India’s first underwater rail tunnel under the Hooghly River for establishing metro link between Howrah and Kolkata has completed before its scheduled deadline of July 2017. The tunnel is 16.6 km long, out of which 10.8 km runs under the ground. Of this 10.8 km, 502 metres is under the water and the whole thing connects Howrah to the west and Salt lake to the east. It will have 12 stations and six will be underground. Estimated cost of the entire project is $750 million or about Rs 5,000 crores. The final commissioning of the project is expected by December 2019, following which it will be operational. The project is built by Afcons Transtonnelstroy and implemented by Kolkata Metro Railway Corporation Ltd (KMRCL).

Because the refractive index of glass is highest, light travels slowly in Glass. 

We know that the speed of light depends on the refraction index. The higher the index of refraction is, the slower the speed of light is.

R.I of air and vacuum = 0 (air is a teeny bit more but can be taken as 0)
R.I of water = 1.33
R.I of glass = 1.4.

Hence, Light travels slowest in Glass.