Question 53

The mass of the pure water and salt equals the mass of the saltwater mixture.

According to the law of conservation of matter, the total mass of a closed system must remain constant over time. When the worker combines pure water with ocean salt, the mass of the resulting saltwater mixture is equal to the combined masses of the water and the salt.

A) The mass of the salt equals the mass of the pure water.

This statement is incorrect because it does not account for the total mass in the system. While the mass of the salt and the mass of the pure water are individual values, they do not equal each other; rather, they contribute to a greater mass when combined.

B) The mass of the salt equals the mass of the saltwater mixture.

This option is incorrect as it confuses the individual mass of the salt with the total mass of the mixture. The mass of the salt alone cannot equal the mass of the saltwater mixture, which includes both the salt and the water.

C) The mass of the pure water equals the mass of the saltwater mixture.

This choice is incorrect because it overlooks the contribution of the salt to the total mass. The mass of the pure water is only a part of the total mass of the saltwater mixture, which also includes the mass of the salt.

D) The mass of the pure water and salt equals the mass of the saltwater mixture.

This statement is correct as it reflects the law of conservation of matter. The total mass before combining (mass of pure water and mass of salt) remains equal to the total mass after the combination (mass of the saltwater mixture), confirming that mass is conserved.

Conclusion

The correct answer, D, accurately represents the law of conservation of matter by stating that the mass of the combined ingredients equals the mass of the resulting mixture. Options A, B, and C fail to acknowledge the total mass involved when combining the salt and water, thereby contradicting the principle of conservation of mass.