Helium is a very light gas that can be used to inflate ballons and give them lift. Hydrogen is a gas that is also lighter than air. Why is Hydrogen not used to inflate balloons?

Hydrogen is a purple gas and can stain objects that it comes in contact with.

It is too light, one small balloon filled with helium is enough to lift a car off the ground

Chemical changes occur when a new substance is formed. Which of the following is a physical change and not a chemical change?

Baking soda reacting with vinegar

Which statement is correct for pure substances?

The substance cannot be split up easily.

The substance must be an element.

The ingredients can be separated.

The substance cannot be split up easily.

The substance must be a compound.

How Well Do You Know Your Chemistry?

1.

Water is a compound that is made from two types of elements. What are the two elements?
- A.
  
  Helium and carbon dioxide
- B.
  
  Hydrogen and Oxygen
- C.
  
  Hydrogen and carbon dioxide
Correct Answer
B. Hydrogen and Oxygen

Explanation
Water is a compound composed of two elements, hydrogen and oxygen. These elements combine chemically to form water molecules, with two hydrogen atoms bonded to one oxygen atom. This chemical composition gives water its unique properties and allows it to exist as a liquid at room temperature.

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2.

When vinegar (or another acid) is added to baking soda (also known as sodium bicarbonate), the mixture fizzes and a gas is produced from the reaction. This gas is called

Correct Answer
Carbon dioxide

Explanation
When vinegar (or another acid) is added to baking soda (sodium bicarbonate), a chemical reaction occurs. The reaction produces carbon dioxide gas, which is responsible for the fizzing observed. This is because the acid reacts with the baking soda to form carbonic acid, which is unstable and decomposes into water and carbon dioxide. Therefore, the correct answer is carbon dioxide.

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3.

Helium is a very light gas that can be used to inflate ballons and give them lift. Hydrogen is a gas that is also lighter than air. Why is Hydrogen not used to inflate balloons?
- A.
  
  It smells bad.
- B.
  
  Hydrogen is a purple gas and can stain objects that it comes in contact with.
- C.
  
  It is too light, one small balloon filled with helium is enough to lift a car off the ground
- D.
  
  It is flammable
Correct Answer
D. It is flammable

Explanation
Hydrogen is not used to inflate balloons because it is flammable. If hydrogen were to come into contact with a flame or spark, it could ignite and cause an explosion. This makes it dangerous to use as a gas for inflating balloons. Helium, on the other hand, is not flammable and is therefore a safer option for this purpose.

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4.

What is the common household name for Sodium chloride?
- A.
  
  Salt
- B.
  
  Baking powder
- C.
  
  Washing powder
- D.
  
  Toothpaste
- E.
  
  Yeast
Correct Answer
A. Salt

Explanation
Sodium chloride is commonly known as salt. It is a white crystalline substance that is widely used as a seasoning and preservative in food. It is also used in various household applications such as cleaning, disinfecting, and water softening. Therefore, the correct answer is salt.

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5.

What are the building blocks of all matter?
- A.
  
  Elements
- B.
  
  Water
- C.
  
  Atoms
- D.
  
  Cells
Correct Answer
C. Atoms

Explanation
Atoms are the building blocks of all matter. They are the smallest units of matter that retain the properties and characteristics of a specific element. Atoms combine to form molecules, which in turn make up all substances and materials in the universe. Therefore, atoms are essential in understanding the composition and behavior of matter.

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6.

The periodic table is a table of ___________

Correct Answer
Elements

Explanation
The periodic table is a table of elements. It organizes all known elements based on their atomic number, electron configuration, and recurring chemical properties. Each element is represented by a unique symbol, and the table is arranged in rows and columns. This arrangement allows scientists to easily identify and study the properties and relationships between different elements.

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7.

Mg is the symbol for what element on the periodic table?
- A.
  
  Mercury
- B.
  
  Zinc
- C.
  
  Lead
- D.
  
  Magnesium
Correct Answer
D. Magnesium

Explanation
Mg is the symbol for Magnesium on the periodic table. Each element on the periodic table is represented by a unique symbol, and Mg is the symbol specifically assigned to Magnesium.

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8.

Chemical changes occur when a new substance is formed. Which of the following is a physical change and not a chemical change?
- A.
  
  Ice melting
- B.
  
  Baking soda reacting with vinegar
- C.
  
  An egg being fried
- D.
  
  Magnesium ribbon being burnt
Correct Answer
A. Ice melting

Explanation
Ice melting is a physical change because it involves a change in state from solid to liquid without the formation of a new substance. In this process, the molecules of ice gain enough energy to break their rigid structure and move more freely, resulting in the formation of liquid water. However, the chemical composition of the substance remains the same.

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9.

Which statement is correct for pure substances?
- A.
  
  The substance must be an element.
- B.
  
  The ingredients can be separated.
- C.
  
  The substance cannot be split up easily.
- D.
  
  The substance must be a compound.
Correct Answer
C. The substance cannot be split up easily.

Explanation
The correct statement for pure substances is that they cannot be split up easily. Pure substances are made up of only one type of element or compound, and they have a fixed composition. They cannot be separated into different components by physical means such as filtration or distillation. This is because the particles in a pure substance are chemically bonded together, making it difficult to break them apart without a chemical reaction.

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10.

What is one indicator that a chemical change has taken place

Correct Answer
Heat
Colour change
Gas
Light
smell

Explanation
One indicator that a chemical change has taken place is a color change. This occurs when the substance being observed changes its color, indicating that a new substance with different chemical properties has been formed. Another indicator is the release of gas, which can be observed through the formation of bubbles or the release of a gas from a reaction. Heat is also a common indicator, as many chemical reactions release or absorb heat. Additionally, the production of light or a noticeable smell can also indicate a chemical change.

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How Well Do You Know Your Chemistry?

Water is a compound that is made from two types of elements. What are the two elements?

When vinegar (or another acid) is added to baking soda (also known as sodium bicarbonate), the mixture fizzes and a gas is produced from the reaction. This gas is called

Helium is a very light gas that can be used to inflate ballons and give them lift. Hydrogen is a gas that is also lighter than air. Why is Hydrogen not used to inflate balloons?

What is the common household name for Sodium chloride?

What are the building blocks of all matter?

The periodic table is a table of ___________

Mg is the symbol for what element on the periodic table?

Chemical changes occur when a new substance is formed. Which of the following is a physical change and not a chemical change?

Which statement is correct for pure substances?

What is one indicator that a chemical change has taken place