Significant Figures
What is the number of significant figures in 0.004506?
4
An element has 17 protons. What is this element?
Chlorine
Convert 1000 mg to grams.
1 g
An isotope has 12 protons and 13 neutrons. What is its mass number?
25
Identify if melting ice is a chemical or physical change.
physical change
Round 7.8562 × 10⁴ to 3 significant figures.
7.86 × 10⁴ or 7860000
Identify whether oxygen is a main group, transition metal, or inner transition metal.
Convert 25°C to Kelvin.
298 K
How many neutrons are in ²³Na?
12
Is flammability a chemical or physical property?
Chemical property
Multiply 6.42 × 2.1 and give the answer with the correct number of significant figures.
13
Name the group (family) of elements that are very unreactive and have a full outer shell of electrons.
Noble Gases
Convert 100°F to Celsius.
37.78°C
An atom of sulfur has 16 protons, 16 neutrons, and 18 electrons. What is its charge?
-2
Identify the type of mixture in which substances are evenly distributed and appear uniform.
Homogeneous mixture
Divide 0.00456 by 2.34 and give the answer with proper significant figures.
0.00195
An element belongs to group 1 of the periodic table. What type of metal is it?
Alkali Metal
A sample has a mass of 5 kg and a volume of 2 L. Calculate the density in g/mL.
2.5 g/mL
Lithium has two isotopes: ⁶Li (7.5%) and ⁷Li (92.5%). Calculate the average atomic mass.
6.9 amu
State the Law of Conservation of Mass in one sentence.
Mass is neither created nor destroyed in a chemical reaction.
Calculate and report the answer with the correct number of significant figures:
(12.11+0.3+1.345)×2.0
27
An element has 7 valence electrons and is in period 3 of the periodic table. Identify the element and its group (family).
Chlorine; Halogens (group 17)
A runner completes a 5 km race in 20 minutes. Convert their speed to meters per second (m/s).
4.17 m/s
An element has three isotopes:
¹⁰X, 19.9% abundance
¹¹X, 80.1% abundance
¹²X, 0.01% abundance
Calculate the average atomic mass of the element.
10.80 amu
Identify whether each of the following is a pure substance, homogeneous mixture, or heterogeneous mixture:
Table salt (NaCl)
Salt water
Oil and water
1. Pure substance
2. Homogeneous mixture
3. Heterogeneous mixture