Types of Pure Substances

What is a compound?

What is $\mathrm{NaCl}$?

Choose the incorrect statement from the following:

Is ${\mathrm{O}}_2$ an element or compound?

Water containing $88.8 \%$ oxygen and $11.2 \%$ hydrogen is often used as a fire extinguisher. Can a mixture containing the two gases in the same ratio by mass be used for extinguishing fire?

Give reason.

Pure substance is made up of similar particle but water is not made up of similar particle and is pure.

Why is blood called a mixture and zinc an element?

Is water a pure substance?

Lavoisier defined as, an element as a basic form of _____ that cannot be broken down Into simpler substances by chemical reactions. 

What did Lavoisier believe were the elements?

Lavoisier defined as, an element as a basic form of matter that cannot be broken down Into simpler substances by chemical reactions. 

Define element according to Lavoisier.

Ozone is an important constituent of the stratosphere as it blocks harmful UV rays from the Sun. Ozone has the chemical formula ${\mathrm{O}}_3$. Which word describes ozone? 

Nylon, like many other plastics, is a long molecule consisting of carbon, nitrogen, oxygen and hydrogen atoms. The first type of nylon was invented by the American chemist, Wallace Carothers in the $1930$s. Its use in clothes, fabrics, ropes and many other things has made it a popular material. What are the drawbacks of using plastics? 

The same elements that are present on the surface of Earth are also present on Mars. For various reasons, they have not combined the same ways to create the life that we see on Earth. Which factors might be important to life to exist? 

Atoms can combine to form complicated compounds. Our genetic identity is stored in a DNA molecule, which contains hundreds of billions of atoms. The structure of DNA is complex, but it is made from only a few different types of atom. Where else can complicated patterns arise from a simple starting point? 

We use different elements and materials in the industry and the source of these elements is from the Earth. Some elements are abundant and easily available. Other elements, such as gold, are rare. Large mines such as this have to be constructed to find gold. Which other important materials do we dig from the Earth? 

Define mixture. What are the types of mixture?

On the basis of chemical composition, substances are classified into.

On the basis of their physical state, substances are classified into