Questions

The submerged portion of the ice on melting shrinks a little in volume. so the level of water goes down a little.But this is just made up by the water added by the melting of upper portion. Addition is equal to the Shrinkage. Hence level is unchanged.

The F1, F2 to F12 keys that are found on the top row of most computer keyboards are called as Function Keys. Unless you've witnessed the evolution of computers from their early days, you probably don't know why they were invented and for what.
Function keys were used by various computer programs to fulfill various functions.

F12 - It is used by many web browsers to open the developer tools.

The stability of the ions is determined by the energy of the lone pairs. Carbon has the least effective nuclear charge (Zeff) and so the lone pair on the CH3− ion has the highest energy, making it the least stable ion and so the strongest base. The Zeff increases as we move across the period until we get to fluorine which has the greatest Zeff and so its lone pairs have the lowest energy, making F− the least basic ion.

In order of decreasing basicity they are ranked LiCH3 > LiNH2 > LiOH > LiF. We are dealing with the ions F−, OH−, NH2− and CH3− and so the factor which influences their basicity is the stability of the ion compared to its conjugate acid.

Italy

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).