A natural disaster is a major event resulting from natural processes of the Earth. It causes a great loss of life and property. During such disasters, the number of people who are rendered, trippled and houseless is more than the number of people who loose their lives. Even the economy of the peace which faces a natural disaster, gets effected.

It is true that a natural disaster is a natural process and we cannot stop it but by making certain preparations, we can reduce the magnitude of the loss to life and property. First of all we should reduce global warming which is the root cause of all the problems. We should also have insurance policies so that we could have sufficient money to rebuilt our lives after any such disaster. The scientists should invent advance warming systems. While construction we should make sure that it is strong enough to withstand earthquakes. We should educate people about evacuation during any disaster.

Kinetic Theory and Gas Pressure
The pressure of a gas is the result of continuous bombardment of the gas molecules against the walls of the container. According to the kinetic theory, the pressure P exerted by an ideal gas is given by

• Boyle’s Law
According to this law, the volume (V) of a fixed mass of a gas is inversely proportional to the pressure (P) of the gas, provided temperature of the gas is kept constant.

• Charle’s Law
According to this law, the volume (V) of a given mass of a gas is directly proportional to the
temperature of the gas, provided pressure of the gas remains constant.

• Gay Lussac’s Law (or Pressure Law)
According to this law, the pressure P of a given mass of a gas is directly proportional to its absolute temperature T, provided the volume V of the gas remains constant.

In the poem 'Photograph', the sea represents timelessness. The poet says that the sea '... appears to have changed less'. The sea is an element of nature where time has little or almost no influence. Sea voyage is a wonderful experience. It sometimes shows that life is like a challenge that a person should face. In that lesson author along with family had determination and courage to face any kind of problems. 

Instantaneous velocity describes how fast an object is moving at different instants of time in a given time interval. It is also defined as average velocity for an infinitely small time interval.

Here lim is taking operation of taking limit with time tending towards 0 or infinitely small.

dx/dt is differential coefficient – Rate of change of position with respect to time at an instant.

Religion has been a subject of study and reflection for a very long time. Sociological findings about society are different from religious reflections. The sociological study of religion is different from a religious or theological study of religion in many ways. One, it conducts empirical studies of how religions actually function in society and its relationship to other institutions. Two, it uses a comparative method. Three, it investigates religious beliefs, practices and institutions in relation to other aspects of society and culture.

Solution:

Let Ф = π/8
2Ф = π/4
tan 2Ф = 1  = 2 tan Ф / [ 1 - tan² Ф ]
1 - tan² Ф = 2 tan Ф
tan² Ф + 2 tan Ф - 1 = 0
tan Ф  =  1/2 [ -2 +- √(4 +4) ]  = -1 +- √2 
tan π/8 is > 0 

Therefore,  tan π/8 = √2 - 1

The contributions: 

1. The Mesopotamians were the first people to introduce the use of the potter's wheel to the world.

2. They were the first to enter into written trade agreement.

3. They also introduced to the world the idea of a written Code of Law.

4. They were the first people to divide a day into 24 hours, an hour into 60 minutes and a minute into 60 seconds.

5. They were first to develop a script and established the libraries and reading rooms.

Singular Sense:
In singular sense, it means the science of counting or science of average. This definition has the following features:

1. Collection of data:
   Most of the statistical analysis is performed on the basis of collected data. The methods of data collection like primary and secondary, census and sampling etc. are related with data collection.
2. Organization of data:
   After collecting data, systematic arrangement is essential. They are organized and presented in table on the basis of rows and columns. This process is known as presentation of data.
3. Analysis of data:
   The organized data presented need to be analyzed. There are various tools of analysis in statistics like average, co-relation, regression, dispersion, etc.
4. Interpretation of data:
   After analysis, results are interpreted and conclusions are drawn. IT is the last and most essential part of the work. If findings are interpreted wrongly, wrong conclusion is obtained.

Plural Sense:
In the plural sense, it refers to the numerical facts and figure systematically collected for some special purpose. This definition has the following features:

1. Statistics are aggregate of facts:
   In statistics, the single numerical figure has no meaning. It is not statistics. The numerical figures of production, income, price of commodities, students of the class etc. are statistics.
2. The values of statistics are numerically expressed:
   The values of statistics are countable as well as numerically expressed. For example, the numbers of students in Siddhartha College in grade 11 are 400. Among them 264 are female and 136 are male, which constitute statistics.
3. Statistics are collected in a systematic manner:
   Firstly, we have to think about the field of study. Then, data should be collected by applying suitable methods and work should be carried out in systematic manner. Otherwise, interpretation and conclusion may be wrong or misleading.
4. Statistics are collected for a pre-determined purpose:
   We must have well defined purpose, specific aims and objectives before we collect data. Suppose, if we want to compare the performance of students in grade XI in Siddhartha College in one subject or more, we must specify the subject and the year, for which comparison is carried out.
5. Statistics makes easy to comparison:
   The collected numerical data constitute statistics if they are comparable. To make valid comparison, the data should be homogeneous. For example, the passed number of students of Siddhartha College and other College constitute statistics, as they are comparable. But weight of the students and their intelligence do not constitute statistics as they are not comparable.