Atomic Structure
How many protons does an atom of the Carbon have?
A) 6
B) 12
C) 18
D) 24
A) 6
What does the Law of Conservation of Mass state?
A) Mass can be created in reactions
B) Mass is destroyed in reactions
C) Mass is neither created nor destroyed
D) Mass changes randomly
C) Mass is neither created nor destroyed
A solution with pH of 3 is:
A) Strongly basic
B) Neutral
C) Strongly acidic
D) Weakly basic
C) Strongly acidic
Which is a physical change?
A) Rusting of iron
B) Burning wood
C) Melting ice
D) Baking a cake
C) Melting ice
What is an isotope?
A) An atom with extra electrons
B) An atom with a different number of protons
C) An atom with a different number of neutrons
D) An atom with a different charge
C) An atom with a different number of neutrons
What type of error occurs due to faulty equipment?
A) Random error
B) Systematic error
C) Human error
D) Experimental error
B) Systematic error
Which reaction represents neutralization?
A) Acid + Metal → Salt + Hydrogen
B) Acid + Base → Salt + Water
C) Acid + Carbonate → Salt + CO₂ + Water
D) Acid + Acid → Salt
B) Acid + Base → Salt + Water
Which is a chemical change?
A) Dissolving sugar in water
B) Evaporating alcohol
C) Freezing water
D) Digesting food
D) Digesting food
If an atom loses electrons, what type of ion does it form?
A) Positive ion
B) Negative ion
C) Neutral atom
D) Isotope
A) Positive ion
Which of these is NOT evidence of a chemical reaction?
A) Color change
B) Temperature change
C) Gas production
D) Melting of ice
D) Melting of ice
Which of these is a base?
A) HCl
B) NaOH
C) CO₂
D) CH₃COOH
B) NaOH
Which observation suggests a chemical change?
A) Shape change
B) Phase change
C) Gas bubbles forming
D) Size reduction
C) Gas bubbles forming
Which particle has no charge?
A) Proton
B) Neutron
C) Electron
D) Ion
B) Neutron
Which statement is true about mass in a chemical reaction?
A) It disappears
B) It is created
C) It is conserved
D) It doubles
C) It is conserved
What does pH measure?
A) Hydrogen ion concentration
B) Temperature
C) Salt content
D) Oxygen level
A) Hydrogen ion concentration
Which process involves breaking chemical bonds?
A) Boiling water
B) Cutting paper
C) Burning gasoline
D) Melting wax
C) Burning gasoline
If an atom gains electrons, what happens?
A) It becomes a positive ion
B) It becomes a negative ion
C) It becomes neutral
D) It becomes an isotope
B) It becomes a negative ion
If a reaction is exothermic, what happens?
A) Heat is absorbed
B) Heat is released
C) Temperature stays constant
D) No energy change
B) Heat is released
What is the pH of pure water?
A) 0
B) 7
C) 14
D) 10
B) 7
Which of these is NOT a chemical change?
A) Cooking an egg
B) Rusting metal
C) Condensing steam
D) Fermenting grapes
C) Condensing steam