Of the following, which does not signify a chemical reaction? 1) tarnish 2) release of heat 3) changing state 4) release of gas

Of the following, which does not signify a chemical reaction?
1) tarnish
2) release of heat
3) changing state
4) release of gas

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  1. A blue liquid is mixed into a yellow liquid, and the mixture turns green.

    A piece of metal is placed in water and produces sparks and gas.

    A liquid is heated on a hotplate, and bubbles form.

    Explanation:

    A chemical reaction occurs when reactants combine or decompose to form products which have a completely different composition and structure than the reactants. There are certain signs which indicate that a chemical reaction has taken place, the primary indicators include:

    1) Formation of a precipitate

    2) Formation of bubbles

    3) color change

    4) change in temperature

    Based on the given examples:

    1) A blue liquid is mixed into a yellow liquid, and the mixture turns green:

    This involves a color change and hence a chemical process

    2) A piece of metal is placed in water and produces sparks and gas.

    Formation of sparks and gas signify a change in temperature and hence a chemical process

    3) A liquid is heated on a hotplate, and bubbles form.

    Formation of bubbles are indicate that a chemical reaction has occured

  2. 2. A piece of metal is placed in water and produces sparks and gas

    Explanation:

    The production of gas is usually a sign of a chemical reaction.  The metal is reacting with the water to form a new substance (the gas).

    Incorrect answers and why:

    1.  Changing colors can be a sign of a chemical reaction, but in this case it's more likely that the colors blended together.  (If it was something like two clear liquids combining to form a yellow liquid, then it would be more clear evidence of a chemical reaction)

    3.  The liquid is boiling

    4.  The powder dissolved into the liquid

    I hope this helps!

  3. 1. Change in temperature

    2. Gas given off (bubbles)

    3. Color change

    4. Salts made

    Happy to help! Please mark as Brainliest!

  4. A solid forms when two liquids are mixed.

    Explanation:

    A physical reaction is defined as the reaction in which a change in shape, size takes place. No new substance gets formed in these reactions.

    A chemical reaction is defined as the reaction in which a change in chemical composition takes place. A new substance is formed in these reactions.

    1. A solid dissolves in liquid: Only the phase of the solid changes to aqueous and no new substance is formed, thus is a physical change.

    2. A solid forms when two liquids are mixed: two liquids can forma  solid only on chemical combination and formation of new substance.

    3. A solid melts to a liquid when it is heated: Only the phase of the solid changes to liquid, no new substance is formed, thus is a physical change.

    4. A solid metal changes shape: Only the shape of the solid changes, thus is a physical change.

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