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WorksheetsDid a Chemical Reaction Take Place
Total questions: 9
Worksheet time: 45mins
A student mixes two substances together in a flask. Which observation could indicate that a chemical reaction is taking place in the flask?
The flask heats up
Bubbles of gas from in the flask
The contents change color
All of these
Which chemical equation correctly demonstrates the law of conservation of mass?
CH4 + 2O2 → CO2 + H2O
H2O2 → 2H2O + O2
2Na + Cl2 → 2NaCl
2NH4OH → 2NH3 + H2O
Which of these activities with eggs involves a chemical reaction?
Frying a raw egg
Scrambling eggs and milk together
Drawing on the shell of a hard-boiled egg
Breaking a raw egg
The photo show a solid as it drops into water and starts producing bubbles. Which statement correctly explains the changes in the solid?
A chemical reaction is happening because the solid is dissolving
A chemical reaction is happening because bubbles are forming
Since bubbles contain only gas, a chemical reaction is not happening
Since no new solid is present, a chemical reaction is not happening
A scientist carried out three experiments and recorded observations in a table. During each experiment, the scientist mixed together two substances. In which experiment did a chemical reaction take place?
Experiment 1
Experiment 2
Experiment 3
All Experiments
All of the following represent chemical reactions except
nails rusting
paper burning
sugar dissolving
leaves decaying
A student used tongs to hold a strip of gray metal ribbon over a small flame. The burning metal ribbon produced a bright light. When the reaction ended, small pieces of white ash remained. The white ash would not burn. Which observation does NOT necessarily show that a chemical reaction took place?
The production of a bright light
The change from one piece of metal to many small pieces
The formation of the new substance in the ash
The change in chemical properties of the solid after it burned
Nitrogen gas (N2) reacts with hydrogen gas (H2) to form ammonia (NH3). Which is a balanced equation that correctly represents this reaction?
N2 + H2 → NH3
N2 + H2 → 2NH3
N2 + 2H2 → 2NH2
N2 + 3H2 → 2NH3
Sodium chloride (NaCl) reacts with sulfuric acid (H2SO4). The products are sodium sulfate (Na2SO4) and hydrochloric acid (HCl). Four students wrote equations to represent this reaction. Which student wrote an equation that demonstrates the law of conservation of mass?
1
2
3
4
