Q4 LONG TEST

How does the Law of Conservation of Mass apply to a burning candle?

• The amount of wax before the reaction equals the amount of energy afterward.

• The mass of the wick before the reaction equals the mass of the smoke afterward.

• The mass of the molecules of the candle before the reaction equals the mass of the candle and burned wick after the reaction.

• The mass of the wick, wax that burned, and the oxygen that helped the flame before the reaction equals the mass of the smoke and the gases released after the reaction.

During a chemical reaction, 50 grams of substance A reacts with 30 grams of substance B to form products. After the reaction, the total mass of the products is measured to be 80 grams. Which statement BEST describes the outcome of this reaction according to the Law of Conservation of Mass?

• The mass of the products is less than the mass of the reactants because some mass is lost during the reaction.

• The mass of the products is greater than the mass of the reactants because some extra mass is gained during the reaction.

• The total mass of the reactants is equal to the total mass of the products because mass cannot be created or destroyed.

• The reaction does not obey the Law of Conservation of Mass because the total mass of the products is different from the total mass of the reactants.

Sarah sees condensation forming on the outside of her cold drink. She knows this is due to water vapor turning into liquid water. What is the correct chemical formula for water?

• CO₂ 

• HCl

• H₂O

• O₂   

Ethan opens a bottle of soda and notices bubbles forming. He knows this is caused by Carbon dioxide being released. Which chemical formula represents Carbon dioxide?

• CH₄ 

• CO  

• CO₂

• C₂O₄

Sodium (Na) forms a Na⁺ ion (with a +1 charge). Oxygen (O) forms an O²⁻ ion (with a -2 charge).

What is the CORRECT formula for Sodium Oxide (Na¹⁺ + O^2-)?

• NaO

• NaO₂    

• Na₂O

• Na₂O₂  

James notices that his old bicycle chain has developed rust after being left in the rain. Rust has the chemical formula Fe₂O₃. What is the CORRECT name of this compound?

                                             

• Iron (III) oxide

• Iron (III) sulfate

• Iron (II) chloride

•    Iron (II) carbonate

Sophia is cooking dinner and uses table salt to season her food. She checks the label and sees the chemical formula NaCl. What is the CORRECT name of this compound?

• Sodium nitrate

• Sodium chloride

• Sodium hydroxide

• Sodium carbonate

Epsom salt, used for relaxing baths and medicinal purposes, has the formula MgSO₄. What is its CORRECT name?

• Magnesium sulfate

• Magnesium chloride

• Magnesium hydroxide

• Magnesium carbonate

What is the correct name of H₂O₂, a mild antiseptic used on the skin to prevent infection of minor cuts, scrapes, and burns?

• Water 

• Oxygen gas

• Sulfuric acid

• Hydrogen peroxide

Be is the symbol for beryllium, which forms a +2 charge. Cl is the symbol for chlorine, which forms a -1 charge. To balance the charges, one beryllium ion (Be²⁺) pairs with two chloride ions (Cl⁻), resulting in the formula BeCl₂. Name the ionic compound: BeCl₂

• Beryllium chlorine

• Beryllium chloride

• Beryllium II chloride

• Beryllium dichloride