B) O^2-
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Answer=3
Electrons carry a negative charge while protons carry a positive charge
Explanation:
Student A would be introducing more error. While student B is subtracting the actual filter paper used in the experiment, Student A is using the mass of a different filter paper, which may have a slightly different mass than the filter paper that was used. To avoid having to aacount for this, or introducing such an error, follow Student B in weighing the filter paper before adding the sand.
I hope this helps.
Answer: Option (3) is the correct answer.
Explanation:
A reaction due to which there occurs change in chemical composition of reactants is known as a chemical reaction.
For example, evolution of heat when two substances combine together shows a chemical reaction has taken place between the substances.
Whereas a reaction which does not bring any changes in chemical composition of the reactants is known as a physical reaction.
For example, boiling point, melting point, mass, volume etc are all physical properties.
Thus, we can conclude that out of the given options a substance melts when sitting in the Sun, is not an indication of a chemical reaction.
True is does make up 90 percent