STAAR REVIEW RC 1: Matter& Energy

Front

A scientist spilled a few drops of dilute hydrochloric acid (HCl) on a lab table. For safety purposes, the scientist sprinkled some baking soda (NaHCO₃) onto the spill. Which observation would provide the best evidence that a chemical reaction occurred?

Back

The baking soda and hydrochloric acid combined and bubbles formed.

Front

Which information could a student determine from only the chemical formula of a protein?

Back

The number of atoms of each element in the protein

Front

In which of these compounds are there twice as many oxygen atoms as hydrogen atoms? Options: H₃PO₄, H₂SO₄, HClO₃, H₂O

Back

H₂SO₄

Front

What is the best evidence that a chemical reaction occurs when coal burns?

Back

A new substance is produced

Front

Aluminum, sulfur, and chlorine are elements found on the periodic table. Tests involving these three elements would show that at normal room temperature-

Back

Aluminum is malleable and conducts electricity

Front

The chemical formula for sodium sulfate is Na₂SO₄. How many sulfur atoms are in the formula for sodium sulfate?

Back

1

Front

How many atoms in all are in a molecule of serotonin?

Back

25

Front

Which balanced equation represents a reaction that involves 14 atoms of oxygen? Options: NH₄Cl + KOH → NH₃ + H₂O + KCl, 2Na + 2H₂O → 2NaOH + H₂, 2C₂H₆ + 7O₂ → 4CO₂ + 6H₂O, 4Fe+ 3O₂ → 2Fe₂O₃

Back

2C₂H₆ + 7O₂ → 4CO₂ + 6H₂O

Front

Atoms present in FOUR molecules of methane (CH₄)?

Back

4 atoms of carbon and 16 atoms of hydrogen

Front

Which statement BEST compares the properties of silicon (S) and nickel (N)?

Back

Silicon is brittle, while nickel is malleable