Question

multiple choice
record your answers on the answer sheet provided by your teacher or on a sheet of paper.

1. which statement about elements is false?

a. the same kind of atoms exist in an element.
b. there are about 1,000 elements found in nature.
c. some elements have been made in laboratories.
d. zinc, copper, and iron are elements.

1. caco₃ is an example of which type of material?

a. element
b. mixture
c. compound
d. colloid
use the graph below to answer question 3.
elements in the universe
hydrogen 93.5%
helium 6.3%
other elements 0.2%

1. what percentage do the elements hydrogen and helium account for in the universe?

a. 100%
b. 99.9%
c. 98%
d. 99.8%

1. the most plentiful element in the universe readily burns in air. what is this chemical property called?

a. flammability
b. ductility
c. density
d. boiling point
use the graph below to answer question 5.
elements in earths crust

1. which element makes up 8 percent of earths crust?

a. iron
b. aluminum
c. silicon
d. oxygen

1. which elements each make up approximately the same percentage of earths crust?

a. iron, calcium, and sodium
b. sodium, potassium, and magnesium
c. oxygen, silicon, and aluminum
d. aluminum, iron, and calcium

1. which statement best describes the conservation of mass?

a. the mass of the products is greater than the mass of the reactants that react in a chemical change.
b. the mass of the reactants is greater than the mass of the products that react in a chemical change.
c. a certain mass of matter is present for a reaction.
d. matter is neither created nor destroyed in a chemical change.

Explanation:

Step1: Analyze question 1

Elements are made of same - kind atoms. There are about 118 known elements (not 1000), some are man - made in labs, and zinc, copper, iron are elements. So B is false.

Step2: Analyze question 2

$CaCO_3$ is made of calcium (Ca), carbon (C), and oxygen (O) atoms chemically combined, so it's a compound. Answer is C.

Step3: Analyze question 3

Hydrogen is 93.5% and helium is 6.3% in the universe. 93.5%+6.3% = 99.8%. Answer is D.

Step4: Analyze question 4

The property of readily burning in air is flammability. Answer is A.

Step5: Analyze question 5

From the graph for Earth's crust, aluminum makes up about 8 percent. Answer is B.

Step6: Analyze question 6

By observing the graph for Earth's crust, sodium, potassium, and magnesium have approximately the same percentage. Answer is B.

Step7: Analyze question 7

The law of conservation of mass states that matter is neither created nor destroyed in a chemical change. Answer is D.

Answer:

1. B. There are about 1,000 elements found in nature.
2. C. compound
3. D. 99.8%
4. A. flammability
5. B. aluminum
6. B. sodium, potassium, and magnesium
7. D. Matter is neither created nor destroyed in a chemical change.