Standard 6 Assessment

Why is it important to balance chemical equations?

• To ensure the reaction occurs faster.

• To satisfy the law of conservation of mass.

• To increase the mass of the products.

• To decrease the mass of the reactants.

Which of the following best explains why mass is conserved in a chemical reaction?

• Atoms are destroyed and created in equal amounts.

• Atoms are rearranged but not created or destroyed.

• Atoms are created but not destroyed.

• Atoms are destroyed but not created.

Which of the following is an example of a chemical reaction that conserves mass?

• Melting ice into water.

• Burning wood to form ash and smoke.

• Dissolving sugar in water.

• Mixing sand and salt.

Which statement is true about the atoms in a chemical reaction?

• Atoms are destroyed in a chemical reaction.

• Atoms are rearranged in a chemical reaction.

• Atoms are created in a chemical reaction.

• Atoms remain unchanged in a chemical reaction.

How can you verify that a chemical equation is balanced?

• By ensuring the number of molecules is the same on both sides.

• By ensuring the number of atoms of each element is the same on both sides.

• By ensuring the total mass is different on both sides.

• By ensuring the number of compounds is the same on both sides.

What is the law of conservation of mass?

• Mass can be created and destroyed in a chemical reaction.

• Mass is neither created nor destroyed in a chemical reaction.

• Mass is always increased in a chemical reaction.

• Mass is always decreased in a chemical reaction.

Which of the following best describes a chemical reaction?

• A process where substances are mixed but not changed.

• A process where substances are changed into different substances.

• A process where substances are destroyed.

• A process where substances are created from nothing.

In a closed system, how does the mass of reactants compare to the mass of products after a chemical reaction?

• The mass of reactants is greater.

• The mass of products is greater.

• The mass of reactants is equal to the mass of products.

• The mass of reactants is less than the mass of products.

Which of the following is a balanced chemical equation?

• $2H_2 + O_2 \rightarrow 2H_2O$

• $H_2 + O_2 \rightarrow H_2O$

• $2H_2 + O_2 \rightarrow H_2O$

• $H_2 + 2O_2 \rightarrow 2H_2O$

Which of the following diagrams best represents the conservation of mass in a chemical reaction?

• A diagram showing more atoms in the products than in the reactants.

• A diagram showing fewer atoms in the products than in the reactants.

• A diagram showing the same number of atoms in both reactants and products.

• A diagram showing no atoms in the products.