Science Practice

What is the trend of valence electrons, from left to right, across a row of the periodic table?

• A. They increase across the period.

• In a period, the number of valence electrons increases (mostly for light metal/elements) as we move from left to right side. However, in a group this periodic trend is constant, that is the number of valence electrons remains the same.

• As you move from left to right across a period, the physical properties of the elements change. One loose trend is the tendency for elemental states to go from solid to liquid to gas across a period. In the extreme cases, Groups 1 and 18, we see that Group-1 elements are all solids and Group-18 elements are all gases.

Which object is smallest?

• A. galaxy

• B. planet

• C. star

• D. universe

An advertisement claims patients can defeat the common cold in 48 hours by taking vitamin C tablets with a mineral supplement. Which is the dependent (responding) variable to test the claim?

• A. the chemical formula for vitamin C

• B. the severity of patients’ cold symptoms

• C. the chemical formula for the mineral supplement

• D. the amount of time before patients’ cold symptoms improve

Students will conduct a laboratory experiment using the following materials: a bunsen burner, a beaker of water, glass tubing, four test tubes containing different chemicals and rubber stoppers. Which of these steps is most critical for students to follow when using these materials to do the lab?

• A. active transport

• B. Wearing eye protection at all times

• C. polypeptides

• A. amino acids

Students are conducting an experiment to determine if sugars are present in foods. They heat a test tube containing a sugar solution in a beaker of water.

Which of these is an unsafe laboratory practice in this experiment?

• D. uranium

• C. nucleotides

• C. induction

• Heating the sugar solution in a closed (stoppered) test tube

Tags

NGSS.MS-ETS1-1

A scientist is testing milk for the presence of bacteria. Exactly 25mL of a test solution must be added to each milk sample. Which of these instruments would most accurately measure the volume of the test solution?

• Catch net and hand lens

• A graduated cylinder

• Heart rate

• Conduct an experiment

Two plant species found in a dry region of the western United States exhibit vastly different abilities to survive. Species A has very slow stem growth and few leaves but is very abundant. Species B has rapid stem growth and many leaves but is very rare. Which hypothesis is most likely supported by this information?

• Extends B over A

• Reduced stem growth may give species A an advantage over species B

• A student hypothesizes that green algae will grow fastest when exposed to blue light. To test this hypothesis, the student should design an experiment with which independent variable?

• Wrong

Tags

NGSS.MS-LS2-1

NGSS.MS-LS2-4

An experiment is conducted to test the effectiveness of four different fertilizers on plant growth. Two grams of each fertilizer were to be diluted in 9 millimeters of water before adding to a plant. Which of the following measuring devices would introduce the least error into the measurement of the 9mL of water?

• 10mL graduated cylinder

• 11mL graduated cylinder

• 8mL graduated cylinder

• 82mL graduated cylinder