15. D is correct, exothermic reactions release heat
I am not sure about 16
The only logical answer is A
Explanation:
A chemical reaction is defined as the reaction in which bonds between the reactants either break or form which leads to the formation of a new substance.
For example,
So, when we drop a sodium metal into water then it produces a frizzing sound which shows the metal is reacting with water.
We know that when two aqueous solutions chemically react with each other then it may lead to the formation of an insoluble substance which is known as precipitate.
This means that formation of a precipitate is also a chemical reaction.
Thus, we can conclude that following are the statements which show evidence for a chemical reaction.
- Dropping sodium metal into water produces fizzing.
- Mixing two aqueous solutions produces a precipitate.
The energy transforms from chemical energy to heat and light energy. Because when the candle burns a chemical reaction occurs, and produces heat and light.
The order would be coefficient, law of conservation of mass, products, and reactants respectively.
<h3>Word matching</h3>
The number written in front of a chemical symbol in an equation is called a coefficient.
The total mass of a system being unchanged is known as the law of conservation of mass
The substances made in chemical reactions are called products.
The starting materials in chemical reactions are called reactants.
More on reactions can be found here: brainly.com/question/17434463
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