Question 1: which of the following is an example of an exothermic chemical reaction?

a. raw dough absorbs heat from the oven and bakes, creating a new substance: bread.

b. a cake is cut into slices

c. liquid water is heated and turns to steam.

d. a firework explodes in the sky and releases heat and light.

question 2: which substance below would be considered a heterogeneous mixture?

a. coffee

b. jello-o

c. trail mix

d. tea

question 3: (2 co2) how many atoms of carbon (c) are represented in the chemical formula shown here?

a. 0 atoms of carbon

b. 2 atoms of carbon

c. 4 atoms of carbon

d. 1 atom of carbon

question 4: which of the following chemical formulas shows an ionic compound?

a. mgo
b. co2
c. n2o
d. c6h12o6

question 5: milk of magnesia is a type of medication people take to with heartburn and indigestion caused by stomach acid. if the ph of this solution is 10.5, which phrase would be a correct description?

a. this substance is basic.

b. this substance will turn blue litmus paper to red.

c. this substance will likely taste sour.

d. this substance is acidic.

question 6: which equation below is balanced to follow the law of conservation of mass?

a. 2 h2 + cl2 = 3 hci
b. 2 h2 + 2 cl2 = 2 hci
c. h2 + cl2 = hci
d. h2 + cl2 = 2 hci

question 7: which of the following chemical formulas shows a covalent compound?

a. mgo
b. naci
c. ch4
d. hbr

question 8: which of these substances is considered a pure substance?

a. air
b. oxygen
c. lemonade
d. mud

question 9: zach used his science kit to find the ph of different solutions around his home. when he tested the lemon juice in the refrigerator, he found that the ph = 4.0.

what would happen if zach dipped a piece of blue litmus paper in the lemon juice solution next?

a. since the lemon juice is acidic, the blue litmus paper would turn red.

b. since the lemon juice is basic, the blue litmus paper would not change color.

c. since the lemon juice is acidic, the blue litmus paper would not change color.

d. since the lemon juice is basic, the blue litmus paper would turn red.

question 10: which of the following is an example of an endothermic chemical reaction?

a. a plant absorbs energy from the sun in order to create sugers during photosynthesis.

b. a loaf of bread is cut into slices.

c. a log burns in a fireplace and releases heat and light

d. a firework explodes in the sky and releases heat and light.