The letter 'E'.

As of the above given data,

It is in the 1st place in Earth, 2nd in Heaven and in the middle of the Sea.

It appears once in a Year and twice in a Week.

It is present in February, June, September, October, November & December.

But not in the Month.

Hence, it is the letter 'E'.

When the switch is ON, in a tube light choke is nothing but the coil/ballast ( inductor) which is used to induce the high voltage across it. as we know that inductor has property to induce high voltage for the brief period of time, this high voltage is required to ionize the gases in the starter.

Then gas inside the starter gets ionized due to this full voltage and heats the bimetallic strip that is caused to be bent to connect to the fixed contact. Current starts flowing through the starter. Although the ionization potential of the neon is the little bit more than that of the argon but still due to small electrode gap high voltage gradient is appeared in the neon bulb and hence glow discharge is started first in a starter.

As voltage gets reduced due to the current causes a voltage drop across the inductor, the strip cools and breaks away from the fixed contact. At that moment a large L di/dt voltage surge comes across the inductor at the time of breaking.

This high valued surge comes across the tube light electrodes and strikes penning mixture (mixture argon gas and mercury vapor).

Gas discharge process continues and current gets the path to flow through the tube light gas only due to low resistance as compared to the resistance of starter.

Chemical weathering is what happens when rocks are broken down and chemically altered.

Chemical weathering is the breakdown of rocks by chemical reactions. Chemical weathering involves changes in the chemical composition of the existing rock to form new rock. Some examples of chemical weathering are hydrolysis, oxidation, carbonation, dissolution, etc.

Here Joystick, Mouse and Scanner are Input devices through which data is given to the computers. But Headphones are output devices through which sound comes as an output from the computer or any devices.

As the frequency of sound is higher, women have shriller voices than men.

The shrillness or pitch of a sound is determined by its frequency. The higher the pitch shriller the voice. As the sounds produced by vocal cords of women are higher than men so women have shriller voices than men. Because their vocal cord is of smaller size. As their vocal cord is more stretched than men's.

Calculating Age has 2 conditions. Let your Birthday is on January 1st.

1. If the month in which you are born is completed in the present year i.e, your birthday, then

Your Age = Present year - Year you are born 

As of now, present year = 2018

i.e, Age = 2018 - 1995 = 23 years.

2. If the month in which you are born is not completed in the present year i.e, your birthday, then

Your Age = Last year - Year you are born

As of now, present year = 2018

i.e, Age = 2017 - 1995 = 22 years.

An amorphous or non-crystalline solid is a solid that lacks the long-range order that is characteristic of a crystal. In Brief, An amorphous solid is any noncrystalline solid in which the atoms and molecules are not organized in a definite lattice pattern. Such solids include glass, plastic, and gel.

Quartz glass (SiO2) is an amorphous solid due to its short range order of constituent particles. Note Quartz is a crystalline solid while quartz glass is an amorphous solid.

DNA - Deoxyribonucleic acid is a type of nucleic acid. The sugar contained in it is called Deoxyribose.