Which of the following is a chemical change?

a. sulfur and iron filings are mixed together in a beaker at room temperature.

b. sulfur and iron filings are mixed together and the iron is removed with a magnet.

c. a mixture of sulfur and iron filings are heated until the contents glow red and the appearance of the mixture changes. a magnet can no longer remove iron filings.

d. a mixture of sulfur and iron filings are placed in carbon disulfide, the sulfur dissolves, leaving iron behind in the bottom of the beaker.

Consider three unlabeled bottles, each contain small pieces of one of the following metals. - magnesium - sodium - silver the following reagents are used for identifying the metals. - pure water - a solution of 1.0 molar hcl - a solution of concentrated hno3 (a) which metal can be easily identified because it is much softer than the other two? describe a chemical test that distinguishes this metal from the other two, using only one of the reagents above. write a balanced chemical equation for the reaction that occurs. (b) one of the other two metals reacts readily with the hcl solution. identify the metal and write the balanced chemical equation for the reaction that occurs when this metal is added to the hcl solution. use the table of standard reduction potentials (attached) to account for the fact that this metal reacts with hcl while the other does not. (c) the one remaining metal reacts with the concentrated hno3 solution. write a balanced chemical equation for the reaction that occurs. (d) the solution obtained in (c) is diluted and a few drops of 1 m hcl is added. describe what would be observed. write a balanced chemical equation for the reaction that occurs.

In the lab, ammonia was mixed with water to form ammonium hydroxide. what is/are the reactant(s)? o water and ammonia o ammonia o ammonium hydroxide need

Ok, so i have 2 questions. try to answer them both: (the topic is fire) 1) how can you represent the chemical reaction of fire? 2) what kind of bond is formed in this chemical reaction