In which situation will checking conservation of mass be most reliable?
Answer and explanation
Correct answer: Measuring total mass before and after reaction in a closed container
The law of conservation of mass states that matter is neither created nor destroyed in a chemical reaction, provided the complete system is considered. A closed container prevents gases, vapours, or solids from leaving, so measuring the total mass before and after gives a reliable comparison. In an open vessel, escaping gas makes the remaining material appear lighter. Colour and smell are observations, not measurements of total mass; therefore option A is correct.
Frequently asked questions
What is the correct answer to this question?
Measuring total mass before and after reaction in a closed container
Why is this the correct answer?
The law of conservation of mass states that matter is neither created nor destroyed in a chemical reaction, provided the complete system is considered. A closed container prevents gases, vapours, or solids from leaving, so measuring the total mass before and after gives a reliable comparison. In an open vessel, escaping gas makes the remaining material appear lighter. Colour and smell are observations, not measurements of total mass; therefore option A is correct.
Which subject and chapter does this question cover?
This is a Class 10 Science question. Chapter: Chemical Substances – Nature and Behaviour. Topic: Chemical Reactions and Equations.
