Notes, summaries, assignments, exams, and problems

Matter: Pure Substances and Mixtures

Matter can be classified into pure substances and mixtures. Pure substances have characteristic properties that do not change under the same conditions of pressure and temperature. They can be identified according to their characteristic properties, such as density and melting point.

Properties of Matter

• Characteristic Properties: These serve to identify substances and do not depend on the amount of the substance.
• Non-Characteristic Properties: These serve to measure or describe substances but not to identify them. They depend on the amount of the substance.

Pure Substances

A pure substance, or chemical substance, is a sample of matter that has a definite chemical composition and cannot be separated into other... Continue reading "The Classification of Matter: Pure Substances, Mixtures, and Solutions" »

Reported Speech Tense Changes

Present Simple

Direct: He works as an editor.

Reported: She said that he worked as an editor.

Present Continuous

Direct: He is working as an editor.

Reported: She said that he was working as an editor.

Past Simple

Direct: He worked as an editor.

Reported: She said that he had worked as an editor.

Past Continuous

Direct: He was working as an editor.

Reported: She said that he had been working as an editor.

Present Perfect Simple

Direct: He has worked as an editor.

Reported: She said that he had worked as an editor.

Present Perfect Continuous

Direct: He has been working as an editor.

Reported: She said that he had been working as an editor.

Past Perfect Simple

Direct: He had worked as an editor.

Reported: She said that he had worked... Continue reading "English Grammar Transformations" »

Educational Challenges in Spain

Nowadays in Spain, there is an educational problem. Most people do not continue with their studies, and 50% of university students leave before finishing their degree. They cannot pay the high tuition fees that the Government has established. Furthermore, there is no job to obtain financial support. To solve this issue, the Government should reduce the price of the tuition fees and make a proper distribution of scholarships because sometimes the Government gives money to people that do not need it. These changes could help many students to continue studying and find a good job to pay for their studies.

Application Letter

Mrs. ...
(School Name)
58, Cardigan Street
Oxford p56 23B

C/ Calderon de la Barca, 29
03201... Continue reading "Educational Challenges in Spain and a Job Application" »

The Cold War: A Summary

The Cold War was a long period of tension between the democracies of the Western World and the communist countries of Eastern Europe. The West was led by the United States, and Eastern Europe was led by the Soviet Union. These two countries became known as superpowers. Although the two superpowers never officially declared war on each other, they fought indirectly in proxy wars, the arms race, and the space race.

Key Events and Turning Points

The Yalta Conference

At Yalta, the future of Poland was discussed. Stalin wanted control of Poland, but the U.S. and U.K. were strongly against it. Britain pointed out that they had entered the war in defense of Poland and could not accept anything but free elections in an independent... Continue reading "Cold War: US-Soviet Tensions & Proxy Conflicts" »

Sole Proprietorship

A sole proprietorship is a business structure where an individual owns and operates the business. The owner contributes the capital, manages operations, and is solely responsible for the business's outcomes. They may work alone or employ others. This structure is the easiest to form and simplest to organize. The sole proprietor can borrow funds or utilize others' money for business purposes.

Advantages of Sole Proprietorship

Easy to Start

Forming a sole proprietorship is easier than partnerships or corporations. There are no legal formalities like agreements, memorandums of association, or articles of association.

Easy to Dissolve

Dissolving a sole proprietorship is simple, as the owner doesn't need permission from shareholders... Continue reading "Sole Proprietorship: Advantages, Disadvantages, and Characteristics" »

Business Studies

The NBER has formally affirmed that the US financial system is in a recession.

By putting into action an effective monetary policy, the Federal Reserve and the US government could uphold stable prices, thus sustaining conditions for long-standing economic expansion as well as increased employment opportunities. This study will explain how open market operations, discount rate, and reserve requirements could be utilized in order to stimulate the American economy.

Open Market Operations

Open market operations (OMOs) refer to the buying and selling of securities by a central bank in the open market to execute monetary policy. OMOs could be utilized in adjusting the supply of reserve balances in order to uphold the federal funds rate... Continue reading "Monetary Policy Tools to Revive the US Economy" »

Key Social Topics in Spain

Right to Education

When we talk about the right education, we refer to the right to a school education for children. In Spain, education is compulsory until sixteen years of age. In underdeveloped countries, a great majority of children do not have this right, and most organizations work for this cause. From my point of view, all people should have this right and be able to make use of it. Rich countries, for example France or the USA, should provide financial support for this cause.

Young People and Family Bonds

In Spain, families and friends are important and very close. A tradition is to gather the entire family on Sundays for lunch and spend the day together. From my experience, my family is very small but we are... Continue reading "Spanish Social Issues: Education, Family, and Consumerism" »

The Real McCoy: A Castle's Ghostly Secret

Four children were staying in an old castle. A rumor circulated that a real ghost haunted the place. However, one child was skeptical. The other three children conspired to imitate ghosts and surprise him. But he saw a ghost that was clearly not one of his friends, a chilling encounter that proved the castle's spectral inhabitant was indeed the real McCoy.

Strange Message: An Astronaut's Legacy

A young girl dreamed of becoming an astronaut. One day, her computer received a strange message. It read: “Follow your dream!” She found this unbelievable, as she had never shared her dream with anyone. Thinking it was a marvel, she replied to the message. Later, she discovered the message had been sent by a... Continue reading "Unexplained Encounters: True Supernatural Stories" »

The Human Circulatory and Respiratory Systems

Key Components and Functions

1. The Diaphragm's Role in Respiration

The diaphragm separates the thoracic cavity (containing the heart, lungs, and ribs) from the abdominal cavity. It plays a crucial role in respiration. As the diaphragm contracts, the volume of the thoracic cavity increases, drawing air into the lungs.

2. Arteries: Transporting Oxygenated Blood

Arteries are large, thick-walled, muscular blood vessels that carry oxygenated blood away from the heart.

• Pulmonary Arteries: Carry deoxygenated blood from the heart to the lungs.
• Umbilical Arteries: Paired arteries (one for each half of the body) found in the abdominal and pelvic regions. They supply deoxygenated blood from the fetus to the placenta