8th Grade MidTerm Review

Nitrogen and nitrogen-containing compounds are involved in many different reactions. Which balanced equation represents a reaction that involves 6 atoms of nitrogen? (TEKS 7.6B)

• N₂ +3H₂ →2NH₃
• 4NH₃ +3O₂ →2N₂ +6H₂O
• 3N₂ +2O₂ →2N₃O₂
• 2NO+O₂ →2NO₂

Sodium bicarbonate, commonly known as baking soda or bicarbonate of soda, is a chemical compound with the formula NaHCO₃. How many different elements are in the compound sodium bicarbonate?

• 1
• 4
• 6
• 7

In the chemical reaction shown below, all of the HCl and Zn will react to form H₂ and ZnCl₂. Which of the following statements describes the result of this reaction? (TEKS 8.6E)

• The hydrogen gas will have a mass of zero
• The zinc chloride will have less mass than the zinc
• The mass of the products will equal the mass of the reactants
• The mass of the hydrogen atoms will decrease in the products

The balanced equation below represents the reaction of NaOH with H₃PO₄. When 20 grams of NaOH reacts with 49 grams of H₃PO₄, 9 grams of water (H₂O) is produced. How many grams of NaH₂PO₄ are produced? (TEKS 8.6E)

• 11 grams
• 60 grams
• 69 grams
• 78 grams

Which of the following is a characteristic of ALL chemical changes? (TEKS 7.6C)

• A different state of matter is produced.
• A new material is formed.
• Some mass is converted to energy.
• Some form of light is given off

The picture shows a girl skiing down a mountain. She is increasing her speed while skiing downhill. Which statements accurately describe the potential and kinetic energy of this skier?

• Kinetic energy increases. Potential energy decreases.
• Kinetic energy increases. Potential energy remains constant.
• Kinetic energy remains constant. Potential energy decreases.
• Kinetic energy remains constant. Potential energy increases.

A distance-time graph represents how far an object has traveled over time, allowing for the visualization of motion and speed. In a distance-time graph, a horizontal line indicates that the object −

• Is moving at a constant speed
• Is speeding up
• Is at rest
• Is accelerating

Which diagram correctly illustrates an unbalanced force being applied to an object?

• 
• 
• 
• 

Which of Newton’s Laws relates to the action of the rider on horse number two?

• When an object is at rest, it will remain at rest.
• The amount of force is equal to mass times acceleration.
• For every action there is an equal and opposite reaction.
• An object in motion continues in the same direction and speed.

The balanced equation below represents the reaction of NaOH with H₃PO₄. When 30 grams of NaOH reacts with 48 grams of H₃PO₄ , 9 grams of NaH₂PO₄ is produced. How many grams of water (H₂O) are produced?

• 11 grams
• 60 grams
• 69 grams
• 78 grams