Question

1. which of the following is a physical property?

a. the flammability of firewood
b. dissolving zinc in hydrochloric acid
c. a nail rusting
d. the color of a bedroom wall

1. ms. smiths class did a science experiment. they combined vinegar and baking soda in a cup, and when the vinegar and baking soda touched each other, they fizzed and bubbled up. the cup overflowed with gases and bubbles. the results of the experiment demonstrated which of the following?

a. a physical change and chemical properties
b. a chemical change and chemical properties
c. a chemical change and physical properties
d. a physical change and physical properties

1. which of the following models best represents a homogeneous mixture?

a. model a because every sample has exactly the same properties.
b. model b because it contains two different elements.
c. model c because it has uniform composition but could be separated.
d. model d because its composition and properties vary throughout the sample.

1. water can be broken down into its constituent elements of hydrogen (h2) and oxygen (o2) using electrolysis. the experiment and reaction are below.

reaction: 2 h2o ⇌ 2 h2+o2
according to the law of conservation of mass, if you reacted 18g of water and formed 16g of oxygen (o2), how many grams of hydrogen should have also been formed?
a. 16g
b. 18g
c. 2g
d. 1g

Explanation:

Step1: Recall the Law of Conservation of Mass

The law states that mass is neither created nor destroyed in a chemical reaction. So, the mass of reactants equals the mass of products.

Step2: Identify reactant and product masses

The mass of water (reactant) is 18g. The mass of oxygen (product) is 16g. Let the mass of hydrogen be $x$ grams.

Step3: Set up the equation

$18g=16g + x$

Step4: Solve for $x$

$x=18g - 16g=2g$

Answer:

C. 2g